Goals from Aiden McGeady, Darren O'Dea, debutant James Forrest and Robbie Keane on Saturday extended the Hoops' winning run in the Scottish Premier League to six games and set them up for the Old Firm derby against Rangers on Tuesday.
Four minutes after the break McGeady beat Well keeper John Ruddy from the edge of the box with a delightful chip and in the 78th minute his cross was headed in from close range by O'Dea.
Forrest came on for McGeady and scored two minutes from time before Keane, on for Morten Rasmussen, made it four in the dying seconds.
Interim boss Lennon had chosen his starting 11 with the Rangers game in mind and it paid off.
Josh Thompson and O'Dea returned to the heart of the defence at the expense of injured Glenn Loovens and Thomas Rogne but Diomansy Kamara and Keane were left on the bench with Lee Naylor and Landry NGuemo out altogether.
In came Edson Braafheid, Georgios Samaras, Zheng Zhi, and Morten Rasmussen.
Parkhead was less than half-full at kick-off, indicating the depth of the disenchantment felt by the Hoops' fans with a torturous season drawing to a close.
The home side started brightly enough and striker Rasmussen had a great chance to open the scoring in the second minute when Braafheid's header back in to the box following a cleared corner landed at the Danish striker's feet.
However, his weak volley from 12 yards went straight to Ruddy, the on-loan keeper back in the Motherwell goal after recovering from a thigh injury.
Moments later, stopper Thompson, who had scored a double the last time the teams met last month, headed a Braafheid corner past the post from eight yards out.
The Parkhead side were in control and in the eighth minute, following good work from Samaras, Ruddy had to push McGeady's left-footed drive from 16 yards round the post for another corner which came to nothing.
Motherwell slowly worked their way in to the game and in the 17th minute Thompson blocked Ross Forbes' goal-bound shot with his foot after good work by midfielder Tom Hateley, who moments later saw his volley go just past the Celtic post.
Occasional moments of class from Celtic, most notably by McGeady and Samaras, were interspersed by far too many mistakes, often by the same two players.
In the 35th minute, after Motherwell defender Stevie Hammell clattered Hoops' striker Marc-Antoine Fortune 25 yards from goal, a training ground move from the resultant free-kick ended with Braafheid firing a shot high over the bar.
Celtic had an escape just before the break thanks to the alertness of keeper Artur Boruc.
Hateley's inswinging corner from the right just before the break had the Poland international scrambling to keep it out, tipping the ball on to the post before Samaras cleared to the relief of the home fans.
The Fir Park side were almost punished at the start of the second half when Hammell's careless pass out of defence was picked up by Scott Brown in the centre circle.
The Hoops' skipper drove in to the right-hand side of the box before hitting a cross which evaded Ruddy and bounced back off the bar.
In the 49th minute, though, McGeady was more deliberate with his effort which gave Celtic the lead.
The Republic of Ireland midfielder's drive from the edge of the box was blocked by Hateley but with some quick thinking, McGeady sent a delightful chip sailing over the helpless Ruddy.
Three minutes later, Samaras drew a good save from the Well keeper with a 20-yard drive.
Fortune got his head on the loose ball to send in to the air and Zheng rose high to head over from just six yards out when the second goal looked likely.
On the hour Keane replaced Rasmussen and moments later the visitors freshened things up when Lukas Jutkiewicz and former Celt Michael McGlinchey came on for Forbes and John Sutton.
Kamara then replaced Samaras while for Motherwell, Chris Humphrey came on for Jim O'Brien.
In the 77th minute Hateley forged his way in to the Celtic box but was thwarted by Boruc as he tried to squeeze the ball in from an acute angle.
But the points were settled a minute later when O'Dea headed in a McGeady cross from close range.
In the 82nd minute Forrest came on for McGeady to make his Celtic debut but minutes later, following a Motherwell corner, it was Hoops' right-back Andreas Hinkel who was handily placed to clear Steven Saunders' volley off the line.
Two minutes from time Forrest ran on to a Fortune knock-on and dinked the ball over Ruddy from 12 yards to make it number three.
In a Celtic breakaway with seconds remaining Keane grabbed the fourth and sent away happy those fans who did turn up.