Representatives for the venue said the singer debuted her 3.5-carat diamond Neil Lane ring at the bash Friday night. Trawick had proposed to her the previous evening in Los Angeles at a private dinner marking his 40th birthday.
Spears and her fiance checked into one of the resort's 3,100-square-foot mega-suites, had dinner at Planet Hollywood's Strip House Steakhouse and ended the evening at Chateau Nightclub, the venue said.
The 30-year-old singer and Trawick met in 2006 and have been dating since 2009.
Swim Week Miami Beach 2014 [PHOTOS]