The future couple first met through mutual acquaintance Kate Moss several years ago, and she has been dating the sports and entertainment manager, who is best friends with David Beckham, since earlier this year.
Rumours had been swirling for weeks, with the 37-year-old Leftovers star adding fuel to the speculation by wearing baggy clothing while out in public in recent times.
Just last Friday she covered up in a heavy woollen coat and held her handbag over her stomach when she stepped out in New York.
And it has now been confirmed Liv Tyler is expecting a baby with her boyfriend Dave Gardner.
The couple are said to be over the moon to be having their first child together.