The Florida Division of Elections accepted the former Republican governor's application at 3:50 p.m. EDT, the Sarasota Herald-Tribune reported.
The newspaper noted Crist registered as a Democrat last December after having campaigned for the re-election of Democratic President Barack Obama.
Crist, who waged an unsuccessful campaign as an independent candidate against Republican Sen. Marco Rubio in 2010, is challenging Republican incumbent Rick Scott. Democrat Nan Rich, a former state senator, also is in the race.
Republican leaders have criticized Crist on a regular basis in advance of his gubernatorial candidacy. Crist spent much of last weekend at the Florida Democratic Convention in Orlando wooing support for his campaign.
"The [Republican] party left me," Crist said in an interview in Orlando last week when asked why he changed his party affiliation.
State GOP Chairman Lenny Curry said in a statement Crist "has now officially filed to run for the position he once abandoned."
He is hold a campaign kickoff event Monday morning in his hometown of St. Petersburg.
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