The Hunger Games actress has succeeded last year’s winner Mila Kunis, who has slipped to sixth place.
Coronation Street star Michelle Keegan is the highest ranking British name, and runner-up overall.
New presenter of ITV’s Good Morning Britain, Susanna Reid, shot up 66 places to finish in 30th position. And the broadcaster and food writer Nigella Lawson made her debut on the list at number 21. At 54, she is the oldest person on the list.
Lawrence, 23, who dates British actor Nicholas Hoult, has become a huge star on the back of her role as Katniss in the Hunger Games series, and landed a best actress Oscar last year for Silver Linings Playbook.
Dan Jude, editor of the FHM 100 Sexiest supplement which is published with the magazine, said: “She’s run away with the title this year and it’s no great surprise. Not only is she the most in-demand actress on the planet, but men the world over have fallen in love with her kooky charm.”
Keegan said of her success: “I’m so flattered. I believe that being sexy isn’t wearing lots of heavy make-up or having the perfect hair or figure — it’s about self-confidence, being comfortable with yourself, smiling and being happy.”
Model Emily Ratajkowski, who appeared naked in Robin Thicke’s video for his single ‘Blurred Lines’, is the highest new entry at number four.
Kate Moss, who turned 40 earlier this year, has returned at number 42, and Countdown brainbox Rachel Riley is the highest riser, shooting up 73 places to number 17.
The biggest drop is for former X Factor judge Tulisa Contostavlos, who has plummeted from last year’s number 11 to this year’s 82. Prince Harry’s ex Cressida Bonas is at 45.
1 (20) Jennifer Lawrence
2 (4) Michelle Keegan
3 (2) Rihanna4 (-) Emily Ratajkowski
5 (6) Kaley Cuoco
6 (1) Mila Kunis
7 (19) Beyonce
8 (-) Lucy Mecklenburgh
9 (54) Nicole Scherzinger
10 (49) Scarlett Johansson