Motherwell's lowest crowd of the season - 3,339 - saw Manuel Pascali head a Gavin Skelton corner past Well goalkeeper Graeme Smith with 10 minutes remaining in the first half to give the visitors the lead.
Killie keeper Alan Combe made a couple of fine saves after the break but any hopes of a comeback for the Steelmen were thwarted in the 76th minute when Russell struck for the first time since arriving from Airdrie United in the summer when he volleyed past Smith from 20 yards.
Kilmarnock manager Jim Jefferies' injury-plagued side recorded only their second win in eight games to put pressure on sixth-placed Aberdeen.
However Motherwell, with one point and one goal from their last six SPL games, do not have their worries to seek as they look forward to a Lanarkshire derby against Hamilton on Saturday.
Neither side went into this live televised game in form but it was a lively enough first half.
In the fourth minute Donovan Simmonds' low drive from 25 yards was spilled by Smith but no Killie player was on hand to take advantage.
Three minutes later, at the other end, Well strike duo Chris Porter and John Sutton linked up well at the edge of the box, the move ending with Porter firing just over the bar from 12 yards out.
Seconds later, the hesitant Porter failed to take advantage of Keith Lasley's searching pass, allowing Killie defender Garry Hay to get in a saving tackle.
In the 12th minute the powerful Simmonds had a good chance from Hay's free-kick but headed weakly straight at Smith from point-blank range. The home side raced up the other end with Sutton rounding Combe after taking a pass from Stephen Hughes but slashing his shot high over the bar from around eight yards out.
As play raged from end to end, Simmonds used his strength to set up Skelton whose angled drive from 18 yards skimmed the angle of post and bar.
There was another injury blow to Kilmarnock's already depleted side on the half-hour mark when Danny Invincibile was carried off on a stretcher after going to ground, the Australian replaced by Iain Flannigan after a few minutes delay.
In the 34th minute Simmonds brilliantly turned Fir Park stopper Mark Reynolds at the edge of the box but back-tracking Saunders got in a saving tackle to concede a corner.
However, the crucial challenge from the youngster had merely delayed the opener for the Ayrshire side.
Skelton's in-swinging corner from the right was met at the front post by Pascali who rose almost unchallenged six yards out to glance the ball past Smith.
Motherwell, subdued by the loss of the goal, started the second half in a more lively if erratic fashion.
However, it was the visitors who first came close to doubling their lead.
In the 51st minute Simmonds battled with Reynolds and as the ball broke to Skelton, the Killie midfielder rattled in a left-footed shot from 25 yards which had Smith diving down low to his left to save.
Moments later, there was a shout for a penalty from the home fans when Pascali appeared to tug the shirt of Porter inside the box as the Fir Park striker tried to get on the end of a Steven McGarry cross but referee Mike Tumilty chose to ignore the claim.
The Steelmen came close to levelling in the 58th minute when Porter cut in from the right and drove in a powerful left-footed shot from the edge of the box which took a deflection before the outstretched Combe tipped the ball on the bar.
Then, in the 67th minute, Porter latched on to a cross-cum-shot by Stephen Hughes to go through on goal against Combe but the Killie keeper was quick off his line to make a fine block, the ball coming off the Motherwell hit-man for a goal kick to add to his frustration.
As the second half progressed, Kilmarnock defended increasingly deep with only the occasional foray forward to threaten the home side.
But in the 76th minute, after indecision in the Fir Park defence, Russell took a Jamie Hamill pass and from 20 yards drove powerfully across Smith and in to the far corner of the net.
It was enough to end any thoughts of a Motherwell comeback.