The 29-year-old actress is expecting her first child with musician husband James Righton, reported E! Online.
Knightley posed for photos at the Luncheon held at the Four Seasons Hotel at Beverly Hills, wearing a loose-fitting black and white dress with a sheer neckline, that concealed her growing baby bump.
Knightley was joined by fellow actress Renee Russo. 'The Imitation Game' and her other movie 'Nightcrawler' were honoured for being part of AFI's films of the year.