Redmayne was crowned Best Actor at the annual event, while Williams accepted her Best Actress honour in a pre-recorded video message.
As he picked up his trophy, Redmayne, who models for top British fashion house Mulberry, quipped, "I've never been in a room with more beautiful people. Can I come back?"
Their joint victory came just a day after both stars lost out in their nominated categories at the British Academy of Film and Television Arts (BAFTA) Awards on Sunday (12Feb12).
Other big winners at Elle's big night included Florence and The Machine frontwoman Florence Welch, who scored the prize for Best Music Act, and period drama Downton Abbey (Best TV Show).
British model-turned-actress Rosie Huntington-Whiteley was named the year's Style Icon, Mad Men's Christina Hendricks took the Best TV star trophy and The Help actress Jessica Chastain was branded the Next Future Icon.