He has written a number of books, winning the Somerset Maugham Award in 1988 for Romantic Affinities.[3] His memoir I Know you're Going to be Happy won the Spear's Memoir of the Year prize in 2013.[4]
Formerly arts editor of Harper's and Queen and deputy arts editor of The Observer, he became opera critic and arts columnist of The Daily Telegraph and dance critic of The Mail on Sunday in 1996. Christiansen sits on the editorial board of Opera magazine. In 2010, he was appointed to the international jury of the Birgit Nilsson Prize.[5] In 2022, he was appointed dance critic of The Spectator and was Dramaturg for Dickie Beau's Showmanism! at the Ustinov Studio, Theatre Royal, Bath.
Formerly a board member of the Charleston Trust (1995–2010) and Gate Theatre (1993–2012), he was appointed to the boards of the Cambridge Arts Theatre and Shadwell Opera in 2016.
In 2009, he entered a civil partnership with the architectural critic Ellis Woodman.[8] He lives in London.
Christiansen stood down as opera critic of The Daily Telegraph in 2020.[9], but continues to write for the paper as a book reviewer and commentator on the arts.