Taylor-Sincalir, out of contract at the Scottish Premiership club, has put pen to paper on a three-year deal until the summer of 2017 and becomes the second new arrival at the DW Stadium following Tuesday's announcement about Andrew Taylor.
Latics boss Uwe Rosler said: "Aaron fits exactly with the type of player we are looking to bring to the club - young, hungry, dynamic and ready to fit into our culture.
"He has been a key player for Partick Thistle for a couple of seasons now and he has been on our radar for some time.
"We will give him the time he needs to become integrated but he has the potential to develop into the sort of player who can take the club forwards."
Taylor-Sinclair made over 100 appearances in all competitions for Thistle since joining in 2011 from Montrose.
Twice voted the Scottish Football League's Young Player of the Month, the 23-year-old was also named in the Scottish First Division's Team of the Year in 2012 and 2013 as Partick secured promotion to the top-flight.
He made 40 appearances for Alan Archibald's side last season, scoring twice, including a winner in a 2-1 win at Kilmarnock in April as the team went on a four-game unbeaten run to secure their Premiership status.
Having sorted out his future, Taylor-Sinclair said: "I can't thank everyone at Partick Thistle enough for the help and support they've given me and I'm leaving some great friends behind, and a superb set of supporters that I'll never forget.
"But when the opportunity to come to Wigan came up, I was very interested, and I feel this is the next step in my career.
"I want to meet up with everyone now, get working and prove to the gaffer that he has made a good choice."
The deal will be officially ratified by the FA and Football League when the international transfer window opens on June 10.