Prater's 37-yard, game-winning kick with 29 seconds remaining in overtime keeps the Broncos (6-5) alive in the race for the AFC West title.
Tebow had a first-down run during the decisive overtime drive, which was highlighted by Willis McGahee's 24-yard scamper to the San Diego 17-yard line.
Tebow, who previously led the Broncos to comeback wins against the Miami Dolphins and New York Jets since taking over as starter, rallied Denver again Sunday, moving them into position for Prater's score-tying, 24-yard field goal with 1:34 left in regulation.
Phillip Rivers went 19-of-36 through the air for 188 yards and a touchdown for the reeling Chargers (4-7), who lost their sixth straight.
LGBT community has 'bullied the American people': Bachmann
McPhee, Cokas 'working on their marriage' after affair