Rivers, though, won't officially take over as coach of the Fairhope, Ala., school until his retirement from the NFL.
"It's a special day for me and my family, really," Rivers told reporters Friday. "I know I'm going to get a little emotional. I've had two childhood dreams -- one was to play in the NFL, and I've been doing that going on my 17th year. The other was to be a high school football coach as my dad did. How blessed am I to live both of these out?"
Rivers was an all-state quarterback while playing for his father, Steve Rivers, at Athens (Ala.) High School before going to play at North Carolina State.
Philip Rivers, who is entering his 17th season in the league, signed a one-year, $25 million contract with the Colts this off-season. The veteran quarterback previously said he is taking it one season at a time, but the Colts hope he can play longer than the one-year pact he signed with them.
The 38-year-old quarterback spent the first 16 years of his NFL career with the Chargers after the franchise acquired him in a 2004 draft-day trade with the New York Giants for Eli Manning. He served as the Chargers' starting quarterback since the 2006 season before parting ways with the organization earlier this off-season.
Philip Rivers, an eight-time Pro Bowl selection, left the Chargers as their franchise leader in 30 different categories, including passing yards (59,271) and touchdown passes (397).