Mashinter, 28, registered 30 points (15 goals, 15 assists) and 70 penalty minutes for the Rockford IceHogs, the American Hockey League affiliate of the Chicago Blackhawks, during the 2016-17 season. He was named the team's MVP.
The 6-foot-4, 225-pound Mashinter will be starting his second stint with the Sharks organization, having originally signed with the team as a free agent on March 3, 2009.
In 471 AHL games, the native of Bradford, Ontario owns 115 goals, 117 assists and 608 penalty minutes.
"Brandon brings a veteran presence to our group and his power forward style of play and leadership qualities will be nice complements to our organization's depth," said Joe Will, the Sharks' assistant general manager and GM of the AHL's San Jose Barracuda. "He has worn a letter each of the last two seasons, and his combination of size and skill earned him his team's MVP honors last season. We are obviously familiar with him both on and off the ice and are excited to welcome him back to San Jose."
Mashinter made his NHL debut on Dec. 29, 2010, with the Sharks. He played in 64 career NHL games with the Sharks, Chicago Blackhawks and New York Rangers, recording four goals, one assist and 50 penalty minutes.