Stewart, 30, spent last season at Gainsborough Trinity after earlier spells with Boston United and Shaw Lane.
Manager Steve Kittrick said: "He'd a quality signing for us who knows this level and those higher very well and his experience will add a lot to our squad this season."
Stewart had spells with Swindon, Portsmouth, Bournemouth and Burnley in the early part of his career.
He said: "I'm really happy to be here, I've played under the manager plenty of times and really enjoyed it so I'm glad to be part of the set up.
"I've come here to be successful, that's the main reason I've signed. The boss has brought in some quality players and I want us to be fighting up near the top end of the table."
Stewart is Kittrick's 13th new signing as only four of last season's squad featured in Saturday's 2-2 draw at Frickley Athletic.
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