[1] Representative roles included: Prince Hamlet,[1] Macbeth,[11] Romeo and Mercutio in Romeo and Juliet,[6][11] Richard II, Richard III,[11] Benedick in Much Ado About Nothing,[1] Shylock in The Merchant of Venice,[12] Orsino in Twelfth Night,[13] Atticus Finch in To Kill a Mockingbird,[14] Jack Tanner in Man and Superman,[11] Christy Mahon in The Playboy of the Western World,[15][1] Young Man in Summertree,[16] Cusins in Major Barbara,[17] Jerry in The Zoo Story, Algernon in The Importance of Being Earnest,[18] Arthur in Camelot,[19] Higgins in My Fair Lady,[20] Matt Friedman in Talley's Folly,[21] David in Social Security,[22] Andrew in Love Letters,[18] Jamie in A Moon for the Misbegotten,[1] Victor in The Price,[18] Jaques in As You Like It,[23] the Dauphin in King John,[11] and Shaw in Dear Liar.

[24] Birney recorded numerous audiobook bestsellers, including works by Dean Koontz,[25] Paul Theroux,[26] Annie Dillard,[27] and Orson Scott Card.

[30][31] Aside from his title role in Bridget Loves Bernie, Birney appeared frequently on television,[1] building a career in TV movies, regular series and miniseries.

Elsewhere, The Adams Chronicles,[1] Glitter,[33] Serpico,[1][34] Fantasy Island, Hawaii Five-O, McMillan & Wife,[32] The F.B.I.,[35] and Murder, She Wrote.

[37] His miniseries credits include Testimony of Two Men, Valley of the Dolls, Night of the Fox, and Master of the Game.

[38] He also appeared in the TV series the Love Boat with his wife where he played an Italian escort to an American woman whose friend arranged the encounter.

Birney also appeared in leading roles in many television films, including Long Journey Home and The Deadly Game.

[39] Birney edited and adapted for the stage a two-character play based on some of Mark Twain’s shorter works and letters.

The piece, Mark Twain's The Diaries of Adam and Eve, was presented on the PBS series American Playhouse.

He was an advisor for the Children’s Rights Council, a national nonprofit organization advocating access to both parents after divorce or separation.