Earlier in the day she had taken to her Twitter page to tell fans how thrilled she was after Jason - who turned 40 on Thursday - had popped the question.
'Still glowing,' she tweeted. 'About to jump on a plane to Planet Hollywood in Vegas.
'Throwing a Bday Party for Jason at Chateau Night Club. So fun. Xxoo.'
Previously, Britney - who recently finished her Femme Fatale world tour - had hinted at the engagement on Twitter, saying: 'OMG. Last night Jason surprised me with the one gift I've been waiting for Can't wait to show you! SO SO SO excited!'
Jason - who was formerly Britney's agent - also confirmed the news yesterday, telling TV show Access Hollywood: 'Yes, we are engaged.'
The couple have been dating since 2009 after Britney ended her relationship with paparazzi snapper Adnan Ghalib.
Although Jason was her agent at the time, he stepped down from the role shortly after they began their relationship.
They briefly worked together earlier this year when he starred as her love interest in the video for her single Criminal.
