The Wales star is back from his mandatory break following the British & Irish Lions' summer tour of South Africa.
And he returns to the 10 shirt, replacing James Grayson, who is not in the matchday squad this week.
Courtney Lawes is also available again, but he will be among the replacements.
There are three changes to the pack that helped to propel Saints past Exeter last week, with Nick Auterac, Paul Hill and Juarno Augustus coming in.
Augustus will make his first Gallagher Premiership start, in place of Teimana Harrison, while Auterac replaces Alex Waller and Hill is in for Ehren Painter.
Saints: Furbank; Sleightholme, Proctor, Dingwall, Collins; Biggar, Mitchell; Auterac, Matavesi, Hill; Ribbans, Ratuniyarawa; Wood, Ludlam (c), Augustus.
Replacements: Fish, Waller, Painter, Coles, Lawes, Harrison, Lomani, Freeman.
London Irish: Parton; Loader, Rona, van Rensburg, Hassell-Collins; Jackson, Phipps; Goodrick-Clarke, Creevy, Hoskins; Simmons, Coleman; Rogerson (c), Donnell, Tuisue.
Replacements: Cornish, Dell, van der Merwe, Nott, Mafi, O’Brien, White, Williams.