Born in Newark, Nottinghamshire, Titmuss grew up in Heckington, Lincolnshire where her parents were teachers. She took her A-levels at Kesteven and Sleaford High School where she played the clarinet. When she was 17, her parents divorced and her father moved to Argyll, Scotland, where he remarried.
Titmuss graduated from City University in St Bartholomew's Hospital in 1998. She did a nursing diploma, because she "was interested in becoming a doctor, but hadn't taken A level Chemistry" and became a staff nurse at London's University College Hospital.
Titmuss was hired as a roving reporter on the Channel 4 programme Richard & Judy, in late 2003, and stated at the time that the job was "an absolute dream come true". She lost her job in January 2004 following allegations of group sex with her boyfriend John Leslie. A sex tape from four years earlier emerged, in which she had been privately filmed having sex with Leslie and aspiring female model Aisha Abubakar. The footage was downloaded without permission from a private computer and made public by "conman" Lanre Onabowale, subsequently convicted to serve 18 years in jail for four counts of rape.
In the 2004 series of Hell's Kitchen, she trained as a chef. In 2005, Titmuss appeared on Channel 4's The Friday Night Project as a regular guest, in Abi Titmuss: A Modern Day Morality Tale, a fly-on-the-wall documentary for Channel 4 and on ITV1's Celebrity Love Island.
She starred on a celebrity edition of Channel 4's Come Dine with Me with Paul Ross, Lesley Joseph, Linda Lusardi and Rodney Marsh.
Titmuss appeared on the reality series Deadline with Janet Street Porter on ITV2. The show followed a number of celebrities as they attempted to produce a celebrity-based magazine each week, published as a supplement to Closer. Titmuss was the fourth celebrity to be sacked from the show.
She has guest-presented shows on Virgin Radio, MTV and LBC radio.
Titmuss took up presenting on pornographic channel Television X, released a fitness video, put her name to an erotic novel published by Black Lace and made personal appearances in nightclubs in the UK and Ireland. An initial offer of a photo shoot over two pages of FHM morphed into a three-page spread and a cover.
In December 2004, Titmuss appeared on the front cover of FHM along with Swedish model Victoria Silvstedt. In 2004 and 2005, she made a total of 38 front-page appearances on British men's magazines, such as FHM, Nuts, Zoo Weekly, Loaded, GQ and Maxim. She also appeared in the Sunday Times Style section and in glamour pictures in several tabloid newspapers, including The Sun, News of the World, Daily Mirror, The People and Daily Star.
In 2005, Titmuss was ranked seventh by readers in FHM's list of 100 Sexiest Women in the World. She started writing a regular sex advice column for the magazine the same year. At the height of her fame in 2004/05, Titmuss would be paid a modelling fee of up to £30,000 a day for appearing on the front page of Nuts or Zoo. In 2005, Titmuss appeared in a high fashion shoot in Pop magazine, which commented on her status as the "face of 21st century celebrity".
In her memoir, Titmuss states how she quickly realised that she wanted more control after seeing magazines pay her for one shoot and then sell the pictures many times over. Accordingly, she started paying for and directing her own shoots, thus owning the copyright over them and selling them herself, along with her manager.
In December 2004, Titmuss appeared on the front cover of FHM again, with Swedish model Victoria Silvstedt, "marking," as she wrote, "the first time a girl was on the FHM cover twice in one year."
After taking a break from modelling, Titmuss relaunched her glamour career in 2007, this time as a brunette, with an appearance on the cover of Zoo Weekly and the sale of the official "Abi Titmuss Calendar". On 25 April that year, it was announced that Titmuss had made an appearance for a third time in FHM's annual 100 Sexiest Women in the World readers' poll, at number 80. She was ranked number 95 in 2004, and number 7 in 2005.
After announcing in late 2007 that she would take a break from her glamour modelling career to concentrate on acting, Titmuss returned with a Nuts shoot in April 2009 to promote one more calendar.
Titmuss first acted during her university studies and then took part-time acting courses at the Central School of Speech and Drama, paid for from her nursing work. After reducing her glamour model work, Titmuss took a further, short, acting course at the same establishment.
According to her memoir, the first theatre producer to audition her for a role was Marc Sinden:
In March 2006, Titmuss made her London theatre acting début, playing a prostitute with a multiple personality disorder in Two Way Mirror by Arthur Miller, at the Courtyard Theatre in King's Cross, for which she won a Fringe Report Award for Best West End Début.
In 2006, Titmuss had a small role in the film Goal! 2 and in 2007 appeared in the second series premiere of Rob Brydon's Annually Retentive, which aired on BBC Three and as a character called Gezebelle in an episode of Katy Brand's Big Ass Show, a sketch comedy series for ITV2.
Between 26 February and 23 March 2008, Titmuss appeared in the black comedy Fat Christ at the King's Head Theatre in Islington, London.
She has been cast in small roles in the British independent films Do Elephants Pray? and Mixed Up. In 2008, she played the "Mysterious Girl" in the Beat 24 Films independent feature film Frontman.
In 2009, Titmuss was cast in the 25th anniversary production of John Godber's play Up 'n' Under at the newly refurbished Hull Truck Theatre, Hull. Titmuss played Hazel, the fitness instructor, starring alongside James Crossley (formerly the "Hunter" in Gladiator) and soap actor Lewis Linford ("Lee Naylor" in Emmerdale). She also had a part in the BBC TV series Hotel Babylon, playing a nun.
From November until December 2009, Titmuss appeared in Shakespeare's Macbeth, playing the character of Lady Macbeth with the Seagull Rep. The production opened at the Seagull Theatre in Lowestoft before transferring to other East Anglian venues.
On 18 February 2012, she played the role of Tara Edmonds in an episode of BBC TV's Casualty. She said that landing the part gave her a sense of self-esteem that she had lost doing the glamour work.
In an article published by The Daily Mail in January 2015, Titmuss announced that she had changed her name to Abigail Evelyn, in the context of her relocation to Hollywood, California and her attempts to establish a new career as an actress.
Titmuss started playing poker "seriously" around 2001. In 2008, Titmuss played in the charity, side-event "Ante Up For Africa" of the World Series of Poker, in Las Vegas. Ladbrokes Poker started sponsoring her in 2005, when she appeared in the first Ladbrokes Poker European Ladies Championship.
In 2005, Titmuss produced a book, co-written with Jayne Lockwood, called Ten Fantasies, in which she reveals her "ten most secret sexual fantasies." She stated that she did not want her mother to read it.
On 24 July 2008, her memoir, titled The Secret Diaries of Abigail Titmuss, on which she collaborated with Heat journalist Lucie Cave, was published by Headline Review. It is written in the form of a diary and is a day-to-day summary of her life for the past six years. It includes an indepth look into the trial of Titmuss' then boyfriend, John Leslie, at the time when he had been accused of rape, her rise to fame and how she dealt with the tabloids invading her life.
Titmuss first came to public attention as the girlfriend of TV presenter John Leslie whom she met in a Fulham bar on 10 April 1999. She also claimed in her memoir that she has had relationships with former footballer and reality television personality Lee Sharpe, whom she met on the ITV1 show Celebrity Love Island, and English actor, author and television presenter David Walliams.