This display was below the level of recent outstanding showings but proved just enough to see off the battling Saddlers – and Stags still carved out enough chances to have won much more handsomely on the day.
Aden Flint gave the home side a 16th minute lead in a first half in which Stags dominated but never quite hit top gear, though Christy Pym was largely a spectator.
But he was beaten by ex-Stag Ryan Stirk with Walsall's first shot on target on 52 minutes.
That shook up the home side but they recovered well and Jordan Bowery restored Stags' advantage on 71 minutes with few scares at the other end after that decisive blow.
Not surprisingly Mansfield were unchanged from the side that won so handsomely in Harrogate on Tuesday night.
That meant Baily Cargill, available again after suspension, had to make do with a place on the bench.
The visitors included two former Stags in Danny Johnson and Ryan Stirk.
There was worry for Stags in the second minute as Gordon sped from halfway into the home box and went down after contact by Flint, but no penalty was given.
On four minutes Bowery crossed from the right and Clarke took the ball on his chest and hit a fierce volley that was blocked.
Evans then did well to grab Maris' corner off the head of Flint at the far post.
On 13 minutes a good interception by Bowery saw him feed Keillor-Dunn, who went off on a run that ended with a low shot straight at Evans.
But Mansfield were ahead from a Maris corner on 16 minutes.
It was floated to the far post where Flint headed it goalwards and the ball bounced up and was kept out by a combination of keeper and crossbar.
A scramble ensued in which Keillor-Dunn's effort was blocked on the line but Flint was on hand to smash the loose ball home from close range.
Akins needed treatment for an injury before the game restarted.
And on 29 minutes he went down again in some discomfort and this time was replaced by Gale.
Walsall survived another six yard box scramble from a Reed free kick and on 36 minutes Maris had a shot deflect wide with Brunt seeing his finish blocked from the resulting corner.
A minute later Evans did well to get a hand to Keillor-Dunn's low finish across him from a tight angle on the left after Clarke had won the ball back for the Stags.
Brunt was booked for a foul on 38 minutes and then Knowles was booked on 39 minutes for tripping Gale in full flight down the left. Macdonald sent the free kick to the far post where Flint was well over with his header.
Ex-Stag Johnson produced his first moment of danger on 43 minutes as he got into the box only to see Bowery stick out a leg and rob him.
Pym punched the first corner up and over his bar and the second was cleared.
Johnson was wide on the turn from 20 yards in the first of five added minutes.
In the fourth Stags could have gone further ahead after Gale stole the ball off Daniels. He squared to Maris who chose not to shoot but set up Keillor-Dunn only to see his shot blocked.
Cargill replaced Brunt for the second half and Mansfield should have been two up within two minutes as Maris set up Lewis for a shot that he sent over the bar from 12 yards.
Instead the visitors drew level on 52 minutes with their first shot on target of the afternoon.
A burst of pace and a low cross from Knowles on the right fell perfectly for Stirk to drill home from 12 yards.
Hutchinson dragged a low shot wide on 58 minutes as the visitors grew in confidence.
Comley was booked for bringing down Keillor-Dunn on 59 minutes and seconds later Gale joined him for a dive in the box.
Stirk wasn't far over with a great shot from 30 yards on the hour mark.
On 70 minutes Bowery curled a tempting ball in front of goal where Gale just unable to reach it and turn it home.
But Mansfield were ahead again on 71 minutes. Swan crossed from the left and Bowery met it first time with not the best of finishes, but the ball somehow found its way in off the inside of the far post.
Thanks to a decoy run by Clarke, Swan was then able to find time to get away a low shot that went wide before Clarke was inches wide from 20 yards.
That was his last action as he was replaced by Boateng for the final 11 minutes.
Keillor-Dunn forced another save from Evans from distance as Stags sought a decisive third.
Boateng quickly saw a booking on 86 minutes for a foul on Tierney.
A minute later Swan set up Boateng for a close range finish that was blocked.
Four added minutes were safely negotiated and Stags preserved their fine record.
STAGS: Pym, Bowery, Flint, Brunt (Cargill HT), Macdonald, Reed, Lewis, Clarke (Boateng 79), Maris (Swan 63), Keillor-Dunn, Akins (Gale 29). SUBS NOT USED: Flinders, Williams, Johnson.
WALSALL: Evans, Okagbue, Gordon, Daniels, Riley, Hutchinson ( James-Taylor 78), Knowles (Allen 88), Comley, Stirk (Matt 82), Tierney, Johnson. SUBS NOT USED: Smith, Foulkes, Griffiths.
REFEREE: David Rock.
ATTENDANCE: 7,641 (778 away).