MK Dons have signed Simon Church, Cody Cropper and Dale Jennings on a busy day of transfer business for boss Karl Robinson.
Sheffield Wednesday skipper Glenn Loovens has signed a new one-year contract with the club.
The 21-year-old stopper is yet to make a first-team appearance for the reigning European champions but has made more than 60 Football League appearances during loan spells with Barnet, Yeovil, Bristol Rovers and Northampton.
Walker's arrival at the Weston Homes Community Stadium seems to suggest manager Joe Dunne will remain in his position, for the time being at least.
Dunne admitted he was considering his future after Saturday's 2-1 home reverse at the hands of fellow strugglers Scunthorpe - a ninth successive league defeat and an unwanted new club record.
Dunne is also close to bringing in another unnamed player, believed to be former loan striker Jabo Ibehre.