John Hughes’ team had designs on closing to within two points of Celtic in the Scottish Premier League but were swept aside by a slick home display.
Doubles from Cillian Sheridan and Liam Craig and a Kenny Deuchar strike saw Derek McInnes’ side ease home in style.
Hibs, who scored through Anthony Stokes, saw their woes compounded by a straight red card for substitute Colin Nish, while an irate Hughes was also sent to the stand.
The visitors made just one change from the loss at Rangers, Derek Riordan coming in for Alan Gow. Centre-half Chris Hogg continued at right-back in place of David Wotherspoon.
St Johnstone had selection problems and made four changes from the defeat at Kilmarnock.
Jody Morris was absent with a stomach problem, along with Peter MacDonald. Paul Sheerin also dropped out, with Danny Grainger not included.
Steven Anderson came in at left-back, while Craig, Deuchar and Kevin Moon were also restored.
The hosts forced the first chance when a loose ball fell to Dave Mackay after a Craig free-kick had only been partially cleared and Hibs goalkeeper Graeme Smith had to push away his drive.
Hibs were struggling with Saints’ aerial presence and after five minutes Craig claimed a fine opener.
Sheridan cushioned Murray Davidson’s header into Craig’s path and he struck a sweet left-footed drive from 20 yards for his sixth of the season.
It was also the sixth league game in a row St Johnstone had struck first and they doubled their advantage on 10 minutes.
This time Craig fed Davidson on the left and he centred for Sheridan to neatly flick past Smith for his first goal since arriving on loan from Celtic.
The one-way traffic continued and Sol Bamba and Hogg, in particular, were enduring a difficult time on the right of defence.
On the half-hour mark Graham Gartland was next to threaten, heading wide Craig’s corner, before Sheridan’s flick from a Chris Millar shot almost sneaked in.
On 35 minutes Smith again came to his side’s rescue, blocking Sheridan’s effort at his near post following another Craig ball down the left flank.
McInnes’ men should have made it three five minutes after the restart.
Anderson’s driven cross was not dealt with by Bamba, the ball breaking clear for Craig who could only weakly strike right-footed at Smith from 15 yards.
Riordan ballooned a shot over at the other end as the visitors finally registered a shot, before Sheridan burst clear only to shoot straight at the Hibs’ keeper. Michael Duberry then headed into Smith’s gloves following a Craig corner.
Hibs’ were at last showing signs of a revival and Anderson had to kick a Riordan drive from almost off his own line.
Hogg’s powerful header was then deflected into the net by Stokes, but the Irishman’s celebrations were cut short by the offside flag.
Hughes rang the changes in search of a goal, Merouane Zemmama and Abdessalam Benjelloun withdrawn for Nish and Wotherspoon.
But it was the Perth outfit who claimed a vital third in the 62nd minute as Sheridan’s fine cross from the left saw Deuchar bullet a header past Smith.
Hibs gave themselves a lifeline five minutes later when Stokes struck his 16th of the season, rounding Smith after a long ball from John Rankin.
But the match swiftly swung back in the hosts’ favour on 70 minutes. First Nish was handed a straight red card by referee Brian Winter for an off-the-ball kick at Duberry.
Sheridan then compounded the visitors’ woe, sweeping home after excellent work from Deuchar.
Hughes’ blood boiled, forcing Winter to send him to the stands after his comments to the fourth official.
Craig put the icing on the cake for the hosts, netting a 78th-minute penalty after Bamba had handled his corner.
Smith got his hands to the spot-kick but the ball squirmed over the line to sum up Hibs’ night.
The only blot for McInnes was a serious-looking injury to Deuchar late on.