Hutchinson slammed the ball home after a Tom Knowles free kick was not held by the Sutton goalkeeper Jack Rose and it was probably just about deserved on the balance of play.
The Saddlers went into the game with any realistic hopes of the play-offs extinguished by a run of just one win in 15 games.
Matty Stevens came in for Andy Williams as Michael Flynn once again shuffled his pack in the search for goals, there was also a return to the bench for Stevens' one-time strike partner Jamille Matt after injury.
Sutton started the day only six points off the play offs but were on a worrying run of no wins and no goals in the last three games. though two of those had been drawn.
After a scrappy opening 15 minutes the first chance came when Sutton's David Ajiboye went past two Walsall players into the area but saw his shot saved by Owen Evans' legs
A minute later the Welsh stopper had to be alert to punch out an in-swinging corner as Sutton tried to take control of the game.
But Walsall eventually came into it and on 19 minutes, good work by Knowles in the left-hand corner saw him pass the ball to Conor Wilkinson whose shot was blocked by the legs of former Saddler Jack Rose.
Donervon Daniels also saw a shot block as he went forward into the area before the action returned to the other end, Evans again required to make a good save from Sutton captain Craig Eastmond.
Joe Low saw a towering header saved by Rose as the attacks ebbed and flowed but it was another set play that proved the undoing of Walsall, as they conceded their third goal in succession from a corner kick.
It came on 31 minutes when Will Randall sent the kick through the Saddlers defence to the far post where Alistair Smith bundled it in for the opening goal.
Sutton seemed to gain in confidence with the goal and continued to look dangerous, another Randall corner on 37 minutes coming out to Craig Eastmond whose shot cannoned off the Walsall defence.
After the break. Flynn brought Liam Gordon and Matt into the fray but it made little difference in the early part of the half, both sides struggling to create chances, though Sutton seemed happy to sit on their lead.
Hutchinson had a shot for Walsall on 63 minutes when he received the ball from a Knowles throw in space but the effort was saved by Rose.
Sutton were content to use spoiling and time wasting tactics when necessary and keep hold of the ball, with Walsall being unable to combat the plan.
Their next shot didn't come until the 84th minute when good work by Williams on the edge of the area saw the ball picked up by substitute Joss Labadie whose shot just went wide of the post.
Hutchinson's last gasp effort came about in the 95th minute when Knowles free kick was not held and he reacted first to score and give Walsall a point from yet another drawn game
15 Good save by Walsall's Owen Evans from Ajiboye
19 Wilkinson for Walsall sees close range shot blocked, as does Donervon Daniels shortly after
31 GOAL Corner by Will Randall for Sutton on the left, ball not cleared Alistair Smith bundles it in at far post
95 GOAL Isaac Hutchinson follows up a free kick from Tom Knowles that wasn't held and turns the ball in
Walsall: (4-3-3) Evans, Daniels (Labadie 75), Monthe, Riley (Maddox 59), Kinsella, Wilkinson (Williams 59), Knowles, McEntee (Gordon 45), Stevens (Matt 45) Hutchinson, Low
Subs not used: Smith, Songo'o
Sutton (4-4-2) Rose, Hart, Goodliffe, Boldewijn, Smith, Bugiel (Kouassi 68), Randall, Eastmond, Ajiboye (Beautyman 79), Kizzi, Wilson (Angol 68)
Subs not used: House, Dundas, Gambin, Milsom