He began his career as a child actor and is best known for his role as Rodney Trotter in the BBC sitcom Only Fools and Horses (1981–2003).

[9] Lyndhurst made his debut as an actor with the uncredited role of Shot Cabin Boy in the historical drama film Bequest to the Nation, which was released on 25 April 1973.

[12] He gained increased national recognition two years later in two BBC sitcom roles - Raymond Fletcher, the teenage son of Ronnie Barker's Norman Stanley Fletcher in Going Straight,[11] and Adam Parkinson, a son of Wendy Craig and Geoffrey Palmer in Carla Lane's Butterflies.

[11] In 1999, he played the villainous Uriah Heep opposite Daniel Radcliffe and Dame Maggie Smith in David Copperfield.

[18] Lyndhurst joined the cast as a regular in the BBC police procedural series New Tricks in 2013, alongside Dennis Waterman and Tamzin Outhwaite.

[19][20] Lyndhurst revived his Goodnight Sweetheart character, Gary Sparrow, in a one-off special episode, which was aired on 2 September 2016.

[21] He played the Governor/Innkeeper in Man of La Mancha for English National Opera at the London Coliseum in 2019, opposite Kelsey Grammer as Cervantes/Quixote, Danielle de Niese as Aldonza/Dulcinea and Peter Polycarpou as Sancho.

[24] Lyndhurst married Lucy Jane Smith[25][26] (born 19 April 1973), a former ballet dancer, in a secret ceremony at St Mary's Church in Chichester, West Sussex on 1 September 1999, having been engaged since 1990.

[34][35] Their son died in his sleep from a brain hemorrhage caused by acute lymphoblastic leukemia[36][37] at the family home in Fulham, Greater London on 22 September 2020, aged 19.