He was born in Harrow, London, England and brought up in Hatch End in Harrow, north-west London. He went to Hatch End Comprehensive School (now Hatch End High School - his brother went to a grammar school instead) and the Central School of Speech and Drama. Philip is the son of director John Glenister and the brother of actor Robert Glenister (probably best known for Hustle). His interest in acting came from seeing his brother in a production about the Sex Pistols called Killing Time at the Soho Poly. He worked for the entertainment entrepreneur Robert Stigwood and then as a films publicist until he was 23. The (former) wife of his brother, the actress Amanda Redman, persuaded him to apply for the Central School of Speech and Drama, and coached him for his audition. At the Central, he was a contemporary of Graham Norton and Rufus Sewell. He also shared a flat with the actor Jamie Glover.
Glenister has appeared in the television drama series Clocking Off (playing the factory boss), Island at War (playing Baron Heinrich von Rheingarten), State of Play, Hornblower, Sharpe (as the titular character's brother), Roger Roger and Vincent, and the film Calendar Girls (playing the photographer). He is probably best known for his role as DCI Gene Hunt in Life On Mars, alongside John Simm's Sam Tyler. Glenister also worked with Simm on State of Play and Clocking Off. He reprised the role of Gene Hunt in the spin-off series Ashes To Ashes, which began on February 7 2008, and worked with Simm on the 1980s-set crime film Tuesday. Upon announcement of the film, Glenister joked that he and Simm were contractually obliged to work with each other once a year. Tuesday premiered in the UK on 10 October 2008.
In the autumn of 2007 he starred as Mr Carter in the BBC1 costume drama Cranford, playing a farmer's son and social reforming estate manager for Lady Ludlow (Francesca Annis).
He also appeared on Top Gear as the Star in a Reasonably Priced Car and achieved a time of 1.54.3 on a wet track.
Glenister played Rupert Galvin, an ex-CIA operative, in the six-part prime time ITV1 drama, Demons, based on Bram Stoker's Dracula in early 2009. In the last few years he has had major roles in Mad Dogs and Big School alongside numerous guest appearances.
Glenister is set to portray Reverend Anderson in a lead role in the upcoming Cinemax series, Outcast.
A book by Glenister on 1970s and 80s culture, Things Ain't What They Used to Be, was published in November 2008.
Glenister married actress Beth Goddard in 2006 after a nine-year relationship. They met at a birthday party for Jamie Glover in July 1997. They have two children, Charlotte (born April 2005) and Millie (born March 2002), and live in East Sheen, near Richmond, London. He supports Arsenal F.C. and is a keen golfer.