Wontner's acting career began on the stage where he played such roles as Tybalt in Romeo and Juliet, Bassanio in The Merchant of Venice, Bunny Manders in Raffles, the Amateur Cracksman and Cardinal Richelieu in The Three Musketeers (1930, West End).

[3][4][5][6] In 1926, Wontner appeared in The Captive alongside Basil Rathbone; both went on to play Sherlock Holmes on film.

Of the five films in which Wontner portrayed Sherlock Holmes, The Missing Rembrandt is no longer available.

[13] Wontner was considered to have a strong resemblance to Sidney Paget's drawings of Holmes featured in The Strand Magazine.

[14] After seeing The Sleeping Cardinal, Vincent Starrett said "Surely no better Sherlock Holmes than Arthur Wontner is likely to be seen and heard in pictures, in our time.