Donato, a natural center who mostly played left wing after arriving from Boston, received a two-year, $3.8 million contract.
He had four goals and 12 assists with 64 shots in 16 games for the Wild last season after the trade with the Bruins.
The 23-year-old has 15 goals and 19 assists in 68 NHL games.
Sturm and Soucy got one-year, two-way deals. Sturm made his Wild debut in April after signing as a college free agent from Clarkson. Soucy spent last season in the AHL.