Freeman hooked up with Tiquan Underwood and Dallas Clark for scoring strikes as the Buccaneers posted their fourth victory in five contests overall.
Doug Martin contributed a combined 119 rushing and receiving yards for Tampa Bay (5-4), which moved over the .500 mark in Week 10.
Philip Rivers was intercepted twice for the Chargers (4-5), who stumbled to their fourth setback in five games. He finished 29-of-37 through the air for 337 yards and three touchdowns in the loss.
Danario Alexander led the Chargers' receiving corps with five catches for 134 yards and a score.