Sheary, 25, had 10 points (seven goals, three assists) as a rookie during the 2015-16 season, then had 10 points (four goals, six assists) in the playoffs to help the Penguins win the Cup.
The undrafted forward has 63 points (30 goals, 33 assists) in 105 games with the Penguins.
"I want to stay consistent with my play and trying to improve on each year," Sheary said. "I don't want to have any slumps or anything like that. I want to make sure I prove myself year in and year out. Hopefully this year I can just keep improving and stay consistent throughout the year and hopefully we can have another good year as a team."
The Penguins also avoided an arbitration hearing with defenseman Brian Dumoulin, agreeing to terms on a six-year, $24 million contract on July 24.
"We're all pretty close friends," Sheary said. "We definitely have congratulated each other. We've said some inside jokes with each other about how much money [Justin Schultz] is making or whatever it may be (three years, $5.5 million per season). But it's all in good fun and I'm happy for those guys as well."