Andrew rejected the offer of a new contract with Grimsby Town in order to make the switch to the Keepmoat.
The move reunites Andrew with Rovers boss Darren Ferguson, who handed him his first professional contract at Peterborough United.
And Ferguson is delighted to add the 26-year-old to his squad.
"This is a really good signing," Ferguson told the Doncaster Free Press.
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"Danny is a very talented boy.
"I've known him since Peterborough when he was a kid.
"He's a lovely lad and has a good character which is important.
"He gives us a left foot that we missed this season.
"He can play left back, left wing back, left centre half in a three.
"I'm delighted to get him in."
Andrew made two senior appearances for Peterborough before being released in the summer of 2010.
He then joined Cheltenham Town where he made 61 appearances over three years, most of them coming in his first season.
After a loan spell with Gloucester City, he joined the Conference North side on a permanent deal for second half of the 2012/13 campaign.
He earned a deal with Conference side Macclesfield Town and featured in every game of the 2013/14 season before being snapped up by League One Fleetwood Town.
His time at Highbury was hit with two major injuries which restricted him to only 18 appearances in two seasons.
Andrew joined Grimsby last summer following his release by Fleetwood.
And he enjoyed a brilliant season at Blundell Park, winning nine prizes at the club's Player of the Season Awards after featuring in every league game.
Grimsby boss Russell Slade was understandably keen for Andrew to remain at Blundell Park and said the club has done all they could to make that happen
"We've done all we can to keep Danny at the club, it's just down to him to decide on where his future lies," Slade told the Grimsby Telegraph.
"We made him an improved offer to keep him here after meeting with him a couple of weeks ago.
"We'll have to wait and see what decision he makes on it."