However, his longing for the stage increased and he was encouraged by great Swedish actor Emil Hillberg in pursuing in acting, after he had witnessed Winnerstrand's striking talent and by offering a place in his theatre company.

Here Winnerstrand rose to star fame in the late 1900s as a top comedy actor, for years performing leading parts in numerous farces and comedies popular of those days by Oscar Wilde, George Bernard Shaw, Georges Feydeau and Georges Berr (in many of the original Swedish stagings of the plays); such as his Mr Ernest in Oscar Wilde's The Importance of Being Earnest, Mr Valentine in Shaw's You Never Can Tell, in Franz Arnold's & Ernst Bach's The Spanish Fly (Die Spanische Fliege; Spanska flugan) and as Vicomte Goring in Wilde's An Ideal Husband.

By 1919 Winnerstrand had made a name for himself as a comedy actor and was asked by the then manager of the national stage, Tor Hedberg, to come and perform at the Royal Dramatic Theatre (Dramaten).

Successful and critically acclaimed parts at Dramaten include his Bo Swedenhielm in Hjalmar Bergman's Swedenhielms (1925), Argan in Molière's The Imaginary Invalid (1927), Pisthetairos in The Birds by Aristophanes (1928), Sir Basil Winterton in Edward Childs Carpenter's The Bachelor Father (1930), Alfred Jingle in Dickens' The Pickwick Club (1931), Chlestakov in Nikolai Gogol's The Inspector General (1932), the King of Babylon in Marc Connelly's The Green Pastures (1932), Måns Sommar in Strindberg's Mäster Olof (1933), Fabrikör Åvik in Birger Sjöbergs Kvartetten som sprängdes (The Quartet That Broke Up) (1935), Nat Miller in Eugene O'Neill's Ah, Wilderness!

(1935–36), Richard Greatham in Noël Coward's Hay Fever (1937), Frank Haines in Dodie Smith's Call It A Day (1937), Titus Jaywood in Mark Reed's Yes, My Darling Daughter (1938), Charles Randolph in Dodie Smith's Dear Octopus (1939), Don Pedro in Shakespeare's Much Ado About Nothing (1940), Fritz Kelemen in Rose Franken's Claudia (1942), Lindgren in Karl Ragnar Gierow's Av hjärtans lust (1945), Hartman in Jean Anouilh's The Wild Bird (1948) and Charley in Arthur Miller's Death of a Salesman (1949).