The Warriors snared 7/53 late on the final day to secure the 36-run win with just seven balls to spare.
Paceman Matt Kelly was the pick of the WA bowlers with 5/63, while David Moody snared three wickets.
Chasing 345 for victory off 70 overs, the West End Redbacks were on track after moving to 3/255 in the 55th over.
But the loss of Ferguson (123 off 154 balls) and Tom Cooper (47 off 69) within six balls of each other hurt SA's victory hopes.
Their dismissals sparked a massive collapse, ending when Adam Zampa (37 off 31 balls) hooked Matt Kelly to fine leg to end the contest.
WA's Ashton Agar provided the highlight of the day when he pulled off a stunning one-handed catch at point to dismiss Redbacks opener Henry Hunt.
Earlier, WA veteran Shaun Marsh cracked an unbeaten 102 to lift WA to 6d/205 in their second innings.
WA started the final day at 4-70 and needing some quick runs to ensure they could build a lead and give themselves enough time to bowl the Redbacks out.
Marsh, who was on 32 overnight, ensured the runs kept ticking over.
Cameron Green (20) and Josh Inglis (1) were the only batsmen to fall in the morning session, with Marsh and Agar (45no) combining for a quick-fire 94-run stand.
The Redbacks arrived in Perth without coach Jamie Siddons, who has been granted personal leave.
Siddons will also miss the upcoming clash with Tasmania.
Former Test batsman Greg Blewett has stepped into the head coach's role in the meantime, with support from high performance manager Tim Nielsen and bowling coach Luke Butterworth.