Hayter, who had missed an earlier penalty, pounced after 17 minutes to earn Bournemouth their first away win since December and only their third win in 15 games.
Two of those wins have come in a five-game unbeaten run that has given Bournemouth some breathing space in the battle for survival.
But for Walsall the future looks extremely bleak as they remain rooted in the drop zone having failed to win a home league game since New Year's Eve.
They have won just once in their last 15 games and their record under recently appointed boss Kevan Broadhurst makes for dismal reading.
A total of just six points have come from his eight games in charge - losing the last three without scoring a goal.
Their dismal evening was perfectly summed up 12 minutes from time when James Constable thought he had salvaged a point only to see his shot from a Dean Keates corner cleared off the line by Stephen Purches.
Hayter should have broken the deadlock four minutes before he did only to see his spot-kick saved by goalkeeper Andy Oakes.
Ian Roper, who conceded a penalty in last Saturday's 3-0 defeat at the hands of Bristol City, was again the guilty party as he hauled down Stephen Cooke.
Hayter tried to beat Oakes at his left-hand post but the former Derby County keeper dived low to turn away his shot.
Fortunately for Hayter he did not have long to wait to make amends.
He responded quickest when Steve Foley lifted a right-wing free-kick into the area and deflected home his shot from six yards.
Despite dominating proceedings, Bournemouth's lead should have been short-lived.
Veteran marksman Steve Claridge missed a golden chance to draw Walsall level in the 22nd minute when he lifted his shot over the bar from just six yards after goalkeeper Gareth Stewart had failed to hold on to a long range drive from Michael Leary.
It was a costly miss for Walsall who were again indebted to Oakes for ensuring they did not slip further behind when he pulled off a wonder save nine minutes before half-time to tip away a shot from Steve Fletcher.
Stewart followed the lead of Oakes to preserve Bournemouth's advantage just a minute into the second half when he beat out a free-kick from Keates.