Hibs prevailed as a thrilling League Cup tie was decided after a nail-biting penalty shoot-out at Fir Park.
'Well led at half time with strikes from Keith Lasley and Michael Higdon overhauling Garry O'Connor's opener.
The visitors created several second-half openings and O'Connor steered in a late Leigh Griffiths delivery for his seventh goal of the season.
Mark Brown then saved from Jamie Murphy and Nicky Law as Hibs converted six of their seven penalties.
The victory sends Colin Calderwood's side into the last eight of the tournament and will lift some of the pressure on the manager after a poor start to the season.
Hibs made all of the early running with O'Connor and Griffiths linking up well and the pair combined for the opening goal on 19 minutes.
The on-loan Wolves forward sent in a precise cross for O'Connor, who neatly converted at the near post.
Griffiths then tried to loft a close range shot over Darren Randolph but the home goalkeeper stretched to make the save.
However, Motherwell immediately responded with their best spell of the game, with winger Chris Humphrey causing mayhem every time he surged forward.
And the hosts were level on the half hour as Lasley struck from 16 yards, Higdon laying on the pass following a Tom Hateley corner.
Law shot narrowly wide but the Fir Parkers were soon in front when the same player found Higdon at the end of a slick one-touch passing move, allowing the striker to sidefoot home from the edge of the penalty area.
Hibs started the second half like a whirlwind and Randolph stretched to parry a Martin Scott shot.
Griffiths tried his luck with a shot from 20 yards that forced another good save from Randolph and was again denied by the goalkeeper from six yards after slipping past Tim Clancy on the right.
Higdon had the chance to add to Motherwell's lead just after the hour but headed over from a Humphrey cross.
Hibs thought they had equalised on 65 minutes after a calamitous mix up from the home defence but O'Connor had pushed the ball into the net with his hand and was duly booked.
Randolph made further saves to thwart substitute Junior Agogo and Victor Palsson but O'Connor equalised by running onto Griffiths' pass three minutes from time and slipping the ball low into the net.
Visiting goalkeeper Brown twice made saves from Law in extra time and Agogo tested Randolph once again, although the tempo had dropped markedly.
'Well substitute Robert McHugh had the ball in the net for Motherwell but was ruled offside ahead of the dramatic shoot-out.
Motherwell manager Stuart McCall: "Hibs started well and we didn't, but once we got going and into our stride we played some smashing stuff. We needed that third goal after coming in at 2-1 at half-time.
"There's no doubt that Hibs deserved to take it to extra-time, as Darren Randolph made two or three excellent saves.
"We had chances to win the game in extra time.
"I've seen Robert McHugh's goal and he was a yard onside and that adds to the pain, but that's football. I understand how tough a job linesmen and referees have and they handled it well tonight."
Hibernian manager Colin Calderwood: "We showed terrific guts to come back in that situation; we lost the game for 20 to 25 minutes after we got the lead but the way we started the game, we should have got to half-time ahead.
"As the second half was going on we looked as if we were maybe exposed a wee bit. The players went for it and it was more or less simplicity in the end - when we did that we were better.
"We had tried too many extravagant balls and ignored easy passes but when we went back to that, were able to move the ball quickly and looked as if we had energy in the team, and we'd have felt aggrieved or anxious if we hadn't scored in that second half as we created chances."