The 28-year-old showed off her svelte figure in a tiny bikini as she splashed along the shores of Oahu, Hawaii on Saturday.
The singer and son Bronx (with Pete Wentz) joined pregnant big sister Jessica, her fiancé Eric Johnson and 7-month-old niece Maxwell Drew for a Hawaiian holiday.
Ashlee – who recently split from Boardwalk Empire actor Vincent Piazza after a year and a half of dating – smiled as she held hands with Bronx, 4.
This holiday season has been all about family for the Simpson clan. Tina Simpson – who filed for divorce from husband of 34 years, Joe Simpson, in October – also joined the girls in Hawaii.