Super-sub Jordan Cook scored a second-half brace to give Sean O'Driscoll the perfect start as Walsall head coach.
The striker broke the deadlock just four minutes after coming on when he fired home from close range after Anthony Forde's shot was parried.
And he made the points safe seven minutes from time, with a fine curling finish into the corner.
The result lifted Walsall up to second in League One, three points behind leaders Burton with a game in hand.
O’Driscoll made two changes to the Saddlers’ starting XI, with Kieron Morris and Milan Lalkovic replacing Sam Mantom and Jordan Cook.
Lalkovic was deployed up front in a 4-2-3-1 formation.
Walsall – with just one win in their last 11 matches against the Valiants – survived an early scare inside three minutes.
From a Vale free-kick, Saddlers keeper Neil Etheridge spilled Ryan McGivern’s header with Richard Duffy bundling home the rebound – only for the goal to be disallowed for offside.
The hosts’ first attempt came after seven minutes, Lalkovic beating the offside trap before firing into the side-netting from an acute angle.
Walsall started to settle into their passing rhythm but were mainly restricted to efforts from distance.
Anthony Forde shot wide from 25 yards and then saw a strike blocked, Morris’ drive was charged down, and Romaine Sawyers twice fired off target.
Vale, victorious on their previous two visits to the Banks’s, created a couple of chances around the half-hour mark.
Duffy headed wide from Michael O’Connor’s free-kick, and Etheridge then made a fine full-length stop to push away Sam Kelly’s swerving left-footed strike.
The home side lacked their usual cutting edge in a quiet first-half but went close ten minutes before the break, Sawyers drilling narrowly wide from 25 yards.
HALF-TIME: WALSALL 0-0 PORT VALE
Rob Page’s Port Vale, who entered the match just four points off the top six, began the second period in the ascendancy.
In-form striker AJ Leitch Smith, with six goals in his previous seven matches, turned smartly in the area and tested Etheridge with a low drive at his near post.
Shortly after, Anthony Grant latched onto a loose ball but fired well over from outside the box.
With Walsall making little headway going forward, O'Driscoll reverted to a 4-4-2 formation with Cook replacing Morris on the hour mark.
And the substitution paid instant dividends, as Cook fired the Saddlers ahead just four minutes later.
Forde’s angled drive was parried by Alnwick and Cook was in the right place to fire home the rebound from close range.
Port Vale pushed for an immediate equaliser, Duffy seeing a looping header tipped over by Etheridge.
Walsall pushed forward to increase their lead with George Evans’ ferocious long-range strike a whisker away from finding the roof of the net.
The Saddlers – clearly buoyed by their goal – threatened again two minutes later, Cook teeing up Forde but Alnwick spread himself well to save with his legs.
And Walsall doubled their advantage seven minutes from time, Cook pouncing on a loose ball to curl a powerful right-footed shot just inside the far post.
FULL-TIME: WALSALL 2-0 PORT VALE
Team: Etheridge, Demetriou, O’Connor, Downing, Taylor, Chambers, Evans (Mantom 90’), Morris (Cook 60’), Sawyers, Forde, Lalkovic.
Subs not used: Roberts, Baxendale, Preston, Flanagan, Kinsella.