Sirianni will work under new Colts head coach Frank Reich, continuing a partnership that existed when both were with the Chargers.
When the Chargers promoted Reich to offensive coordinator prior to the 2014 season, Sirianni took over Reich's role as the team's quarterbacks coach.
Since then, Reich has moved on first to the Philadelphia Eagles and now the top job in Indianapolis.
Sirianni transitioned from QBs coach to wide receivers coach, a position he has filled for the past two seasons.
The 36-year-old played collegiately at the University of Mount Union, where he won three Division III national championships (2000-02) as a wide receiver.