Lionel Ainsworth and Luke Watt were on target with second half goals for the Scottish Premiership club at the Energy Assets Arena.
It was Motherwell’s first win of pre-season after draws with Borussia Mönchengladbach and Heerenveen and a defeat against Bradford
Motherwell opened the scoring just before the hour when Ainsworth latched on to a lofted pass from David Clarkson and after quickly controlling the ball he despatched his shot past Darren Jamieson.
Ainsworth turned provider on 72 minutes when he flicked the ball into the path of the overlapping Watt to cut inside a defender and crash a low drive past the ‘keeper.
Elsewhere, Robert Thomson scored the decisive goal 20 minutes from time at Glebe Park as League One side Brechin beat Dundee 1-0.
Newly promoted Hearts lost 1-0 against English Sky Bet Championship team Preston North End at Deepdale.
The goal arrived on 63 minutes when Hearts goalkeeper Neil Alexander sliced a clearance across the penalty area and Joe Garner netted with a header.
Relegated St Mirren also lost 1-0 to English opponents, this time at home to League One Bradford.
Billy Clarke struck with just 13 minutes gone at St Mirren Park when he slipped the ball through the legs of ‘keeper Marc Ridgers.
Fellow Championship promotion hopefuls Hibernian had a comfortable 2-1 victory over League One Dunfermline at East End Park.
The Pars had defender Jason Talbot dismissed on 20 minutes for going over the ball in a challenge with Hibs striker Dominique Malonga.
And the visitors took the lead when Scott Allan curled a shot into the top corner from the edge of the D on 34 minutes.
Five minutes after the break Jason Cummings cut the ball back into the penalty area and Lewis Stevenson netted from close-range.
Dunfermline pulled a goal back five minutes from the end when Faissal El-Bakhtaoui sent a low shot under Antonio Reguero.
Meanwhile, Rory McAllister’s goal on 20 minutes was enough to give Peterhead a 1-0 win over an Aberdeen XI at Balmoor.