Justin who turned 28 on Saturday was stunned when he arrived at Los Angeles' Hollywood Roosevelt Hotel's lavish penthouse suite to find his friends and family waiting to celebrate his special day.
Jessica, 26, had planned a Super Bowl-themed bash for the
singer and the penthouse had several large flat-screen TVs so guests could watch the famous American football match.
A source said: "Justin was totally blown away when he walked in. He had no idea." The 100 guests – including Justin's best friend Trace Ayala, the singer's cousins and Jessica's brothers – were treated to pizza, buffalo wings and red velvet cupcakes.
Jessica and Justin, who have been dating for over a year, looked more in love than ever at the party.
The source added to People magazine: "They held hands and relaxed. They seemed very happy together." Justin wasn't the only celebrity to celebrate his birthday over the weekend.
Ellen DeGeneres and Portia de Rossi - who got married last August - threw a star-studded joint party at their Beverly Hills house on Saturday.
Ellen – who turned 51 on January 26 – and Portia – who was 36 on January 31 invited Jennifer Aniston, Courteney Cox and her husband David Arquette, Drew Barrymore, Sacha Baron Cohen and Ben Stiller to help them mark their special days.
A source said: "This is their first big party together as a married couple. Ellen and Portia seem very excited to have all their friends here."
DJ Samantha Ronson played a set in the couple's backyard and was accompanied by her girlfriend Lindsay Lohan. Guests enjoyed a lavish vegan meal.