Reese Witherspoon Celebrates 40th Birthday By Singing 'Sweet Home Alabama'

The Oscar winner is celebrating the big day on March 22.

— -- It looks like Reese Witherspoon is starting her birthday celebration early.

The actress, who will turn 40 on March 22, feted her big day with a party at the Warwick, in Hollywood, California, according to People magazine.

Along with her husband Jim Toth, the Oscar winner celebrated with Taylor Swift, who performed, Robert Downey Jr. and wife Susan Downey, Jennifer Aniston and husband Justin Theroux, Matthew McConaughey and wife Camila Alves, Tobey Maguire and wife Jennifer Meyer, Courteney Cox, and Kate Hudson, who posted photos of the party.

Keith Urban was also in attendance, along with his wife Nicole Kidman, and performed for the birthday girl. Witherspoon also got up on stage when the country singer performed "Sweet Home Alabama," a nod to the actress hit 2002 romantic comedy.

Witherspoon was excited before her party even began. She posted a couple of photos on Instagram, including one with her mother, Betty Reese.