He is eligible to make his Rovers debut in Saturday’s season opener against AFC Wimbledon with his registration completed prior to Friday’s deadline.
The versatile midfielder has been on trial with the club since the start of pre-season and featured in the friendlies against Rossington Main, Sheffield United and Harrogate Town.
Gardner’s versatility proved attractive for Rovers boss Richie Wellens with the 31-year-old able to play on both flanks or operate as an attacking or deeper-lying midfielder.
He departed Wigan Athletic at the end of last season after making 40 appearances for the Latics.
Gardner started his professional career with Celtic after being spotted as an 18-year-old.
After leaving Celtic in 2009, and barring a short spell with Crewe Alexandra, he spent almost five years with various non-league clubs until he joined Chesterfield in January 2014.
He was part of an incredibly successful period for the Spireites which saw them pushing for promotion to the Championship.
Gardner had a two-year spell with Oldham Athletic which was blighted by a knee injury and did not play league football for a year until joining Wigan.