The couple are celebrating
The Gossip Girl actress, 27, is planning her wedding after Adam, 33, got down on one knee, reports our US sister site People.
The couple met on the set of 2011 film The Oranges and their romance was confirmed in February when they were spotted cuddling up after dinner in California.
At the time, they were said to have been dating ‘for weeks’.
Leighton split from Gossip Girl co-star Sebastian Stan in 2010, which she described as ‘really sad’ but said that the relationhip had taught her a lot about ‘herself and love and life’.
Curly-haired hottie Adam ended things with with Rachel Bilson after three years in 2006.
SEE PICTURES Leighton Meester celebrates her Flaunt Magazine cover in LA
SEE PICTURES Leighton Meester and Chace Crawford share a moment on the set of Gossip Girl
SEE PICTURES Leighton Meester at the MTV Movie Awards 2012