The 26-year-old Melrose Place star has filed for divorce from Wentz, 31, citing “irreconcilable differences”.
According to documents filed at Los Angeles Superior Court, Simpson is asking for primary physical custody and joint legal custody of their two-year-old son, Bronx. She has also requested spousal and child support.
US reports claim the couple did not sign a pre-nuptial agreement before their May 2008 wedding.
News of their divorce comes just three months after her sister Jessica Simpson announced her engagement to American football player Eric Johnson.