It was quickly established that Jack is a morally ambiguous character with a murky past in the police force resulting in the paralysis of his young daughter, Penny (Mia McKenna-Bruce).

Since returning, his storylines have included reuniting with Ronnie Mitchell (Samantha Womack), gaining custody of his son Ricky Mitchell (Henri Charles/Frankie Day), finding out Ronnie had drowned on their wedding day and his subsequent grief over her death, a custody battle with Charlie Cotton (Declan Bennett) over his stepson Matthew Mitchell Cotton, supporting his great-niece Tiffany Butcher (Maisie Smith) over her rape and confronting her attacker, rejoining the police force, relationships with Mel Owen (Tamzin Outhwaite) and Denise Fox (Diane Parish), discovering that Amy has been self-harming, dealing with his son Ricky becoming a father at twelve-years-old, an affair with Stacey Slater (Lacey Turner), helping The Six conceal their involvement in the murder of Keanu Taylor (Danny Walters), dealing with Amy being temporarily paralysed after a crush at Peggy's Nightclub, framing Penny (now Kitty Castledine) for causing the crush, and being blackmailed by Harry Mitchell (Elijah Holloway).

He praised the show's executive producer Diederick Santer for his development of new, "strong characters", including Jack Branning and Roxy and Ronnie Mitchell.

"[7] Maslen himself pointed out that the character of Jack was actually higher ranking than Phil Hunter, joking: "I've been promoted from playing a DS in Sun Hill!

"[18] Executive producer Lorraine Newman said, "Since October 2007, Scott Maslen has brought the wonderful Jack Branning to life on our screens.

Jack is the youngest child of Jim (John Bardon) and Reenie Branning (Joy Graham) and brother of Derek (Terence Beesley; Jamie Foreman), Carol (Lindsey Coulson), April (Debbie Arnold), Suzy (Julie Christian-Young; Maggie O'Neill) and Max (Jake Wood).

Having grown up in a large family in a poor area of East London, Jack regularly fought his older brother, Max, for the attentions of his father who was an alcoholic.

He was very close friends with Michael Moon (Steve John Shepherd), another local East End boy who went to school with him and had a closer relationship with him than he did with his brothers.

Penny's spinal cord was severed, putting her in a wheelchair and, in the aftermath, Jack and Selina divorced and he retired from the police force.

Jack comes to Walford for his nephew Bradley Branning's (Charlie Clements) wedding to Stacey Slater (Lacey Turner).

A fight with Max leads to Jack's wedding invitation being revoked, so he stays at The Queen Victoria public house and helps Ronnie's sister Roxy (Rita Simons) prepare for the reception.

Jack blackmails Phil with this, demanding the car lot for his silence, which he then rents to Pat Evans (Pam St Clement).

Ronnie and Jack discuss the possibility of a baby but he refuses, telling her she needs to grieve for her deceased daughter, Danielle Jones (Lauren Crace).

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.

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.

Jack then agrees to go on a blind date set up by Tanya and Zainab Masood (Nina Wadia), but is horrified when he discovers it is with Denise.

Jack later expresses his attraction to Sharon Watts (Letitia Dean), who has jilted her fiancé John Hewland (Jesse Birdsall).

Mick later tells Jack that Roxy's fiancé Dean Wicks (Matt Di Angelo) raped his wife, Linda Carter (Kellie Bright).

Ray confronts Jack and threatens to expose his past as a police officer and the events that led to Penny becoming paralyzed if he doesn't stay away from Mel.

Jack agrees to help them escape, but tips off the police about Mel's plans to flee the country with Hunter, leading to his arrest.

Jack's happiness is short-lived when he beats up drug dealer Fraser Shelton (Shanu Hazzan) when he finds out that he has raped his grand-niece Tiffany Butcher (Maisie Smith).

In April 2022, Jack is surprised to see Ricky's (now Frankie Day) mother Sam (now Kim Medcalf) back in Walford.

In January 2023, it is revealed that twelve-year-old Lily Slater (Lillia Turner) has fallen pregnant and she names Jack and Sam’s son Ricky as the father following a one-night stand.

The murder causes Denise to have a mental breakdown and be committed to a special facility, and, Jack slowly deduces that something is strange about Keanu's disappearance.

In August 2024, Amy is severely injured during a crush at Peggy's Nightclub; Jack blames Penny (now Kitty Castledine) whilst it is in fact Chelsea who is responsible, which Denise later discovers.

Fearing that Chelsea will be separated from her son Jordan Fox if the truth is revealed, Jack convinces a majority of the family that Penny should instead take the blame for the offence.

[23] However, The Times were more critical, writing of 2007's New Year's Eve episode: "The alleged erotic tension between Ronnie Mitchell (Samantha Womack) and Jack Branning (Scott Maslen) was so underplayed as to be invisible.

"[24] A reporter writing for the Inside Soap Yearbook 2017 (released in November 2016) described Jack's return as "a great arrival", before adding that he "made a very attractive birthday gift for Walford's Ronnie".

[28] Scenes broadcast on 3 January 2017, in which Jack struggles to tell Amy and Ricky that Ronnie and Roxy have died, were praised by bereaved children's charity Grief Encounter.

[29] In 2020, Sara Wallis and Ian Hyland from The Daily Mirror placed Jack 44th on their ranked list of the best EastEnders characters of all time, calling him a "ladies man" and commenting that he "has been hailed one of the Square’s hottest properties since 2007.