The result takes the Phoenix into fifth place, with games in hand on four of the other teams in the top six.
It was the perfect fillip, ahead of the long-awaited homecoming game in Wellington next Sunday against the Central Coast Mariners, after the trip to face Perth Glory on Wednesday.
What unfolded on Saturday was a brilliant turnaround.
In other Phoenix seasons, shipping 11 goals in less than a week would have been the start of a downward spiral and evidence of a crisis.
But this team seems to have an unbreakable spirit and those results felt circumstantial, with the Covid issues and the absence of numerous regulars.
Piscopo and Sotirio added another dimension, while Gael Sandoval provided class in a central midfield role.
Coach Ufuk Talay also pulled a considerable surprise, using a 5-4-1 formation for the first time in his tenure, which caught Western United out in first half.
Tim Payne solidified a central back three, alongside Finn Surman and Scott Wootton, with Callan Elliott and Sam Sutton employed as wing backs, while Oli Sail underlined his importance with some strong saves.
Wellington took a while to click into gear, given the formation and personnel changes.
Western United made the stronger start, with a couple of half chances falling to Lachlan Wales, before Wellington settled into their patterns.
The Phoenix took the lead in the 28th minute, as Wootton tucked home at the far post after David Ball flicked on a whipped Sandoval corner.
That was a vital breakthrough, ending a period of almost four hours without a Phoenix goal, before they doubled their advantage just three minutes later.
Sotirio, who had looked dangerous, smashed home from the edge of the area, via a deflection. Sandoval provided the assist, after Nicholas Pennington's well-timed tackle started the counter attack.
Piscopo then went close, before an excellent half was capped off by Sandoval's cool penalty, placing the spot kick just inside the left-hand upright, after a clumsy Ben Garuccio challenge on Pennington.
Steve Lustica provided a route back for Western United with a smart finish, after neat work on the edge of the area, but Sotirio stamped out any hopes of a comeback with a sharp turn and finish eight minutes later, after Piscopo's perfect cut back.
The Phoenix managed the game from there, though Sail denied Garuccio with sharp reflexes and Wootton was fortunate after a strong late penalty appeal by the home side.
Wellington Phoenix 4 (Scott Wootton 29, Jaushua Sotirio 32, 63 Gael Sandoval pen 45+2)
Western United 1 (Steve Lustica 54)
Halftime: 3-0
