The actress paraded around in a sexy red bikini while enjoying a vacation in Barbados with Hayden to celebrate his 30th birthday.
Bilson, 29, looked stunning in the tiny two-piece and spent the day swimming in the Caribbean sea and strolling around the white sandy beach.
Gorgeous: Rachel Bilson looked stunning in a tiny red bikini as she enjoyed the sunshine in Barbados today on a trip with boyfriend Hayden Christensen to celebrate his 30th birthday
Vacation time: The 29-year-old former O.C. star looked relaxed and happy as she took a dip in the ocean
She showcased off her muscular stomach and toned physique in the string swimsuit and looked like she did not have a care in the world.
The couple later went for a stroll, dressed casually in shorts and T-shirts and carrying their beach bags while soaking up the time on their tropical getaway.
The Waiting For Forever star and her Star Wars beau roamed the Bajan streets and checked out the offerings of local vendors.
Relaxation: Bilson had made an appearance at the Tribeca Film Festival on Thursday night to debut her new commercials for Magnum ice cream before jetting to the paradise island
She and her on-again off-again boyfriend jetted to the paradise island after Rachel made an appearance at the Tribeca Film Festival on Thursday night to debut her new commercials for Magnum ice cream.
Hayden actually turned 30 on Tuesday but they had to fulfil her promotional duties before they could set off for some rest and relaxation.
This sunshine holiday is the first time that Hayden and Rachel have been spotted together for some time.
Rekindled: Rachel and Hayden began dating in 2007 but have been on and off over the years including having a broken engagement in August last year but got back together after a few months
The couple first began dating in 2007 after meeting on the set of Jumper, and became engaged a year later, but they've weathered several breakups and makeups since then.
The couple called off their engagement in August last year. It came as reports emerged that the two actors were taking a break earlier in the year.
A representative for Bilson, who starred in The O.C., told People magazine: 'Yes, the engagement is off.
Work commitments meant the couple had been living separate lives, with Rachel based in Los Angeles, while Hayden was in Canada.
Made for each other: The couple met on the set of a movie and worked together again on 2009 film New York, I Love You
The distance between them was one of the main reasons for the split, a friend said.
'It just wasn't working out,' the friend told People, adding that Bilson was 'focusing on her career, spending time with her family and just moving forward.'
But three months later in November 2010, it appeared that the couple couldn't bear to be apart and reportedly started dating again.
And now they appear to be getting completely back on track. They worked together again two years into their relationship in 2009 on one of 11 short films that made up New York, I Love You.
Bilson previously dated Adam Brody, her co-star on The O.C., for three years. Since leaving the show she has moved into film, and was seen earlier this year in Waiting For Forever opposite Tom Sturridge.
Change: The 29-year-old's figure was impeccably toned in a black skimpy two-piece she wore yesterday
All eyes on Rachel: Boyfriend Hayden Christensen couldn't take his eyes off his stunning girlfriend
- via Daily Mail