E! News reported Monday that Todd -- a commercial fisherman and oil field worker -- filed for divorce in Alaska on Friday.
"Incompatibility of temperament" was the reason for the breakup cited in court documents, according to The Anchorage Daily News.
Todd requested joint legal custody of their 11-year-old son, Trig.
The one-time, high-school sweethearts are also the parents of four adult children -- Willow, Track, Piper and media personality and Dancing with the Stars alum, Bristol Palin.
Since leaving politics, Sarah Palin has served as a commentator on Fox News and host of the docu-series, Amazing America with Sarah Palin and Sarah Palin's Alaska. She also penned an autobiography called Going Rogue.