The Ducks on Thursday also signed free-agent defenseman Shane O'Brien and second-round draft pick Julius Nattinen.
Wagner made his NHL debut last season, going scoreless in nine regular-season games and two playoff games. The former fifth-round pick was an AHL All-Star, and he is expected to contend for a regular role with the Ducks next season.
O'Brien will turn 32 next month. He broke into the NHL with Anaheim in 2006, playing in 62 games before the Ducks traded him to Tampa Bay. He has suited up for seven teams in his career, scoring 92 points in 537 games.
The Ducks acquired Sgarbossa from Colorado last season. He has played nine NHL games with the Avalanche.