Jack settled down with Selina and on marrying, they had a daughter, Penny. Jack built a career in the police force but got involved in criminal activities and when they backfired, one of Jack's informants knocked Selina and Penny down in revenge for being accidentally sent down. Penny's spinal cord was severed, putting her in a wheelchair, and in the aftermath, Jack and Selina divorced and Jack retired from the police force.
Jack comes to Walford on 29 October 2007 for his nephew Bradley Branning's wedding to Stacey Slater. Upon his arrival, Jack soaks Ronnie Mitchell when driving through a puddle, so she soaks him with her water bottle. A fight with Max leads to Jack's invitation being revoked so he stays at The Queen Victoria public house and helps Ronnie's sister Roxy Mitchell prepare for the reception. Deciding to stick around, Jack comes between Ronnie and Roxy when he buys Scarlet Nightclub and offers Ronnie a partnership. Jack causes more disruption in the Mitchell family when he sets up Ronnie's cousin, Phil Mitchell, by taping him confessing to his part in Kevin Wicks's death by selling him cut-and-shut cars. Jack blackmails Phil with this, demanding the car lot for his silence (which he then rents to Pat Evans).
Despite the Mitchells' animosity, Jack falls in love with Ronnie, and after kissing on Christmas Day 2007, they start dating. However, their relationship is rocky as the Mitchells, particularly Roxy, try splitting them up. Jack's ex-wife, Selina, reappears briefly and they have a one-night stand, which Roxy finds out about and tells Ronnie, who is about to move in with Jack but changes her mind, ending their relationship. They reconcile briefly in April but Ronnie does not trust Jack and struggles to bond with his daughter, Penny. Raw from losing Ronnie, Jack and Roxy have a drunken one-night stand. Both regret it and agree not to tell anyone but Roxy is pregnant, giving birth to her daughter, Amy, on 14 November 2008.
Jack starts dating Tanya, who is now estranged from Max. Jack supports Tanya and her children as they struggle to cope after discovering Max's affair with Stacey and his departure, although they do not have sex. However, Max returns and is furious to discover that they are together. Max tries buying the family home but Jack outbids him, buying 5 Albert Square and moving in with Tanya and the children. Max tries coming between them but is unsuccessful. Much to Max's horror, Tanya forgives him and in desperation, Max tries framing Jack, claiming Jack tried to kill him. Jack is arrested but soon released, due to his connections in the police force and lack of evidence and inconsistencies. In revenge, Jack takes Max hostage, beating him and taunting him before abandoning him in an old warehouse. Later that night, Max is mowed down by a car and Jack is prime suspect. Max's daughter, Lauren, later confesses and, to save Lauren from prison, Tanya confesses to the police and is arrested in November 2008 when she ends her relationship with Jack, leading them both to reveal that they don't love each other, don't care a bit about each other, and were just using each other to get back at max
Glad to be free of Tanya, Jack demands a DNA test on Amy, Roxy's daughter. Roxy reluctantly agrees but tells him that Sean is Amy's father. Jack concentrates on re-building his relationship with Ronnie, with whom he now shares a flat. However, on Christmas Day 2008, Jack's sister Suzy reveals the true result – Jack is Amy's father. Furious, Sean snatches Amy and persuades Roxy to join him on a trip to Dagenham. However, Sean tries to kill them by driving into a frozen lake. Jack and Ronnie appear and save Roxy and Amy. On returning to Walford, Roxy tells Jack that he will have no contact with Amy and Ronnie refuses to reconcile with him. Jack tries establishing regular contact with Amy, leading Ronnie to leave Walford. Racing to the airport to stop her, Jack tells Ronnie that he loves her over the airport tannoy. They return to Walford together and Roxy agrees not to interfere. Ronnie and Jack discuss having a baby but he refuses, telling her she needs time to grieve for her daughter, Danielle Jones. Jack asks Ronnie to marry him but catches her piercing condoms. They argue, and Jack storms out, but finds Ronnie's ring on the table when he returns. After telling Jack that Ronnie has left Walford for good, Roxy tries seducing Jack but he pushes her away. When Ronnie returns, Jack begs her to reunite with him, but she refuses. A few weeks later, she asks him to buy her out of the nightclub and to fund this, Jack sells the car lot to Archie Mitchell, Ronnie's father (who she despises). This distances Ronnie further from Jack.
The feud between Jack and Phil recommences. Phil discovers that Jack is dealing drugs and when Shirley Carter buys drugs from one of his contacts, Phil forces Jack to buy them back. Humiliated, Jack employs Phil's sister Sam Mitchell, infuriating Phil. Despite knowing she is engaged to Ricky Butcher, Jack and Sam begin an affair. Archie intervenes and pays Jack to keep seeing Sam, part of his plan to take over The Queen Victoria pub. He also tells Jack's niece/Ricky's ex-wife Bianca about the affair. Later, Bianca drags Sam into The Queen Victoria and forces her to tell Ricky (in front of her uncle Jack) about the affair she was having. Jack is distraught as Roxy was about to give him Ronnie's address but when the affair is revealed, Roxy changes her mind and throws him out of the pub.
Ronnie gets pregnant but she has a miscarriage when Archie pushes her against the bar in the pub during an argument. Jack comforts Ronnie and takes in Ronnie, Roxy and Amy when they are made homeless by Archie. Jack confronts Archie on Christmas Day and threatens to kill him if he hurts Ronnie and Amy again. Archie is murdered that day and an investigation begins. Four weeks later, Jack asks Ronnie to dinner, to which she agrees but not until after Archie's funeral. At the funeral, Jack offers DC Wayne Hughes to help with any "local information" he might need. He later sees Ronnie tearing up the flowers on Archie's grave and asks her why and she thinks he is accusing her of murder. She later sees him talking to DCI Jill Marsden, who is investigating the murder. Ronnie asks Jack how he would feel if he knew she had killed Archie, leading him to suspect her. At his great niece Tiffany Dean's birthday party, he cuts his hand and Tiffany tells him that she saw Bradley washing blood off his hands on Christmas Day. Jack confronts Bradley who eventually reveals that he found out from Stacey on Christmas Day that Archie had raped and impregnated her, and Bradley punched Archie.
Jack urges Bradley to go to the police, saying if he doesn't, Jack will. However, Max stops him and when DNA screening starts and Bradley gives a sample, Jack bribes Hughes to make the DNA samples disappear. Janine is arrested when someone plants Archie's mother's missing engagement ring in her flat, and Jack hears from Hughes when she is being released. Jack offers Janine money to leave Walford and they accuse each other. He says he did not set her up and Ryan Malloy (Neil McDermott) stops him from hurting Janine. Later, Jack receives another call from Hughes to say that someone has reported Bradley and he is about to be arrested. Jack tells Bradley he must leave Walford quickly, and says he will meet them soon and help them to go. However, Jack is delayed by police and when Bradley realises he has left his passport behind, he returns to the Square where police see him and chase him to the roof of The Queen Victoria, where he kills himself.
Jack begins a relationship with Chelsea Fox after helping her escape from a blind date (although he is merely using her to make Ronnie jealous and doesn't care a bit about her). He organises a party his niece Lauren at R&R, where Kylie attempts to shoot Jack's nephew Billie but Jack is shot instead as he pushes Billie out of the way. Jack is taken to hospital, where doctors tell his family he may be left with severe brain damage. He is put in a medically induced coma and undergoes an operation due to swelling on his brain, which is successful. When he is brought out of the coma, it is discovered that he is paralysed down the left side of his body but it is not clear whether it is periodic or permanent. Jack then breaks up with Chelsea and attempts to phone Ronnie, but she does not hear her phone ringing as she is spending time with Jack's consultant, Mr Steele. He starts to feel helpless and wants to give up, but after Max refuses to help him, he puts his phone out of reach and manages to pull himself up with one arm.
Max reveals to Jack that he saw Ronnie and Mr Steele kissing, so Jack punches Mr Steele out of jealousy. When Ronnie discovers this, she dumps Mr Steele and rushes to see Jack, telling him that if he were to propose, she would not turn him down. Billie visits Jack to apologise, but Jack ignores his apology as it has taken him weeks to visit him, calling him cowardly. Billie leaves in tears and then joins the army to make Jack proud of him. Ronnie visits again and is told that Jack was able to move his toe earlier. She thinks Jack needs better care so decides to find him a place at a private clinic. Jack later hears from Max that there has been a fire at the club, and Ronnie tells him he is going to the clinic. However, she decides not to claim on the insurance to keep Billy Mitchell out of trouble. Roxy hears from Max that Ronnie has no money and is not claiming, so she decides to pay for Jack's treatment and he is moved to the private clinic. Jack makes decent progress and when Ronnie visits him, they end up having sex. A few days later, having been discharged from hospital, Jack turns up in The Queen Victoria for Ronnie's birthday. Later, when they return to his flat, Jack asks Ronnie to marry him and she accepts. When he finds out that Archie raped Ronnie when she was 13 years old, he finds it hard to believe at first because she would have known about it for several years without telling anybody, however, he tells Ronnie he does believe her and vows to not let anyone hurt her again. He becomes frustrated when his progress at physiotherapy slows down. He is determined to walk at his own wedding but Max says he never will, and makes him angry, goading him into getting out of his wheelchair.
Ronnie discovers that Sam is pregnant and tells Jack, asking if it could be his even though Sam insists it is Ricky's. After the baby is born, Sam admits she is unsure. Jack and Ronnie visit Sam and the baby in hospital. Even though Sam now says that baby, Richard, is Ricky's, Bianca tells Jack he should see if Richard is his. He and Ronnie both agree and tell Sam, and Ricky also agrees to a paternity test. Ronnie tells Jack whatever the result is, they will be okay. Sam reveals that the paternity test confirmed Ricky as the father. Ronnie and Jack are relieved and Ronnie reveals that she is pregnant with Jack's baby. However, a suspicious Bianca gets the paternity results for herself, and reveals that the father is actually Jack. Sam then tells them that Ronnie made her lie. Ronnie tells Jack she did not want to share him with anyone else, and Jack understands. Later, Sam visits Jack and Ronnie saying she cannot cope with the baby on her own, and asks them to have him. Ronnie and Jack agree but when they are due to meet, Sam does not turn up. Ronnie visits Sam and tells her to keep Richard but offers her money to leave Walford as when Jack finds out he will come looking for her. Ronnie returns to Jack but finds Sam has already dropped Richard off. Ronnie then meets Sam with cash and tells her to take Richard back but she will have to leave straight away. Sam leaves the next day.
Before Billie's birthday, he visits Jack but Jack tells him to leave, however, he goes to Billie's party. Billie and Kylie's friend Connor Stanley turns up and apologises to Jack on behalf of Kylie. Kylie is sentenced to 15 years in prison. The day before Jack and Ronnie's wedding, Jack helps Max take revenge on Harry Gold who is harassing his ex-wife Vanessa, Max's girlfriend. They threaten Harry and tell him to stay away, but afterwards Jack is grabbed by two men and bundled into a car. The next day, nobody is able to find Jack but Max finds his phone. He drives Ronnie to the wedding and finds Jack in the boot of the wedding car, tied up and gagged. Max frees him and Jack and Ronnie get married. After, they leave for their honeymoon.
After the honeymoon, Jack goes abroad on business and is unable to return to see Ronnie give birth to their son James. Before Jack returns, James dies due to cot death but Ronnie swaps their dead baby with Alfie and Kat Moon's newborn baby, Tommy. Jack is introduced to Tommy as his own son, and bonds with him. However, he worries about Ronnie's state of mind when she struggles to cope. Jack sells his share in R&R and goes into business with Max at the car lot, renaming it Branning Brothers. He then meets Michael Moon, Alfie's cousin who he knows from his youth, and invites him to stay but Ronnie finds out Michael is Tommy's real father and tells Jack to kick him out, which Jack eventually does. When Jack announces he and Michael are opening a boxing club, Ronnie is infuriated, so she lies that Michael came onto her. Jack punches Michael but Michael tells him that Ronnie is obsessed with him and has stolen a passport photo of him, which Jack later finds with Ronnie's things. He confronts her, but says is she does not know why she took it, but insists she does not want Michael near the baby. He quits the car lot to look after the boxing club full-time. He starts to worry about Ronnie's erratic behaviour. Eventually, she tells Jack that he is not the father, and hands Tommy back to Kat and Alfie. Tommy is taken into care and Jack says an emotional goodbye, while Ronnie is in police custody. Jack visits her in prison, but she tells him to forget he ever met her and find someone else. He brutally beats Max but they reconcile the day after on Max's birthday.
Jack later starts a relationship with Sharon Rickman and becomes a father figure to Dennis Rickman Jr. Later on, he proposes to Sharon and she happily accepts. Shortly before the wedding, he is sent a letter telling him Ronnie is being released from prison. Jack reevaluates his relationship with Sharon and decides he doesn't love her the way he loves Ronnie. Jack jilted Sharon at the alter, leaving Sharon to run back into Phil's arms.
In September 2013, Ronnie returns and Jack is immediately wary of her, however the two passionately kiss in the R&R office after Jack tells her that he isn't going to let her push him away again. It seems like everything is back on track between the couple, however Ronnie admits to him she can't be with him anymore after all that has happened, leading Jack to pack his bags and depart Walford on the 15th October 2013.
On December 2015, Jack returns to Walford to spend time with his daughter Amy, while his romance with Ronnie seems to quickly show signs of rekindling he is immediately exposed to much of the trouble Ronnie is getting herself into, albeit ill informed.