The ‘Harry Potter’ star was joined by friends and family at Mayfair’s Automat Club and Restaurant, in London, where she was showered with gifts.
Emma – who has starred as Hermione Granger in five ‘Harry Potter’ movies since 2001 – looked stunning in a strapless black mini-dress.
Guests at the party included Tom Felton, who stars as the villainous Draco Malfoy in the ‘Harry Potter’ movies, Evanna Lynch, who plays Luna Lovegood, and Katie Leung, who portrays Harry's love interest Cho Chang.
Daniel Radcliffe and Rupert Grint, who play Harry and his close friend Ron Weasley respectively, were not able to attend.
When Emma turned 18 last week she gained access to the £10.5 million fortune she has earned from the ‘Harry Potter’ films.
She is rumoured to be earning £2.5 million to appear in sixth film 'Harry Potter and the Half-Blood Prince’.
Her fee was increased by studio bosses after she threatened to pull out of the lucrative franchise to attend university.
The Harry Potter star finally managed to conjure a smile later as the mountains of presents arrived, including a, er, tree.
Surely a magic potion of booze on your 18th is more fitting potion - especially when you've just become old enough to tap into your £10m trust fund.