The attacking midfielder put pen to paper on a three-year deal after Hearts were able to negotiate an early exit from his contract down south. No fee was involved.
Walker becomes Craig Levein’s third signing of the summer. The 26-year-old joins Livingston defender Craig Halkett and Northern Irish forward Conor Washington in strengthening the Hearts squad for next season.
Walker signed for Wigan in January 2018 for a reported fee of £300,000 with his contract running down.
He failed to set the heather alight in Lancashire, making just two starts and nine appearances in total.
He spent the first half of last season on loan at Peterborough United, enjoying marginally better success with 17 appearances (eight starts) and two goals scored before undergoing a knee operation.
He returns to the club with whom he won the 2014-15 Scottish Championship title after initially breaking into the first-team squad in the 2012-13 season.
In total he made 182 appearances for the Gorgie Road club, scoring 40 goals and winning the supporter’s player of the year award in 2017.