Hewitt will play "seasoned undercover agent" Katie Callahan, "whose stellar work at the FBI has landed her a coveted position with the Behavioral Analysis Unit."
"We're thrilled to introduce a new special agent by adding the very talented Jennifer Love Hewitt to our amazing cast," showrunner Erica Messer said in a statement. "Many of us on the show have enjoyed working with her over the years and look forward to again. We have exciting storylines planned for her character and the entire BAU team as we head into our 10th season."
Hewitt's last starred on Lifetime's The Client List, which ended abruptly last year over reported differences between the 35-year-old actress and its showrunner.
Hewitt will appear in the tenth season premiere of Criminal Minds on Wednesday, October 1.