Stephen Hughes scored the game's only goal as Rangers prevailed in a scrappy match played in difficult conditions.
Stephen Hughes is congratulated by Michael Mols
High winds and a badly rutted playing surface caused problems for both sides but Motherwell kept Ibrox keeper Stefan Klos busy in the opening 45 minutes.
Rangers went ahead on the stroke of half time when Hughes' low drive across goal found the far corner of the net.
In a bad-tempered second half Gordon Marshall kept the home side in the game with two fine saves.
Motherwell keeper Marshall gave the home fans a scare after just two minutes when he kicked the ball to the feet of Michael Mols 30 yards out and the Dutch striker tried his luck with a shot which flew high over the crossbar.
Scott McDonald was looking lively up front for Motherwell and the young Australian met Shaun Fagan's cross with a header just a couple of yards out but Klos was alert enough to make the save.
With a stiff breeze behind them, Motherwell were moving forward with menace, while Rangers' build up play was often ponderous and unimaginative.
McDonald scurried away from Rangers skipper Craig Moore but elected to shoot from a tight angle and Klos was able to block the effort.
Klos had to smother an 18 yard shot from Hammell then did well to get in the way of a Steven Craig header from close range.
Paul Quinn rose highest to head a Jason Dair corner towards goal but Klos managed to get his fingertips to the ball and tip it over the crossbar.
Hammell fizzed a powerful shot over the top, while the best Rangers could offer were long-range strikes from Hamed Naouchi and Hughes that Marshall did well to hold.
But with 44 minutes gone Mols managed to slip a quick pass to Hughes inside the penalty area and the midfielder's lunging cross-cum-shot rolled across the face of goal and crept in at the far post.
Stefan Klos made some good saves in the first half
When the second half got underway Rangers looked much more assured in defence and the best the home side could manage was a 25 yard drive from Dair that flew wide.
With 62 minutes gone Hammell curled in a useful free kick but Klos was able to gather comfortably.
Rangers were seeing more of the ball but struggled to create any meaningful openings in front of goal until Steven Thompson warmed the hands of Marshall with a powerful strike.
The veteran keeper then made a superb reaction save to keep out a glancing header from Mols.
The closing stages saw some desperate defending at both ends and neither side had the guile to add to the scoreline.
Rangers are now 17 points behind league leaders Celtic, while Motherwell stay in sixth spot - five points ahead of Livingston and Hibs.
Motherwell: Marshall, Quinn, Craigan, Corrigan, Hammell, Fagan, Burns, Dair, O'Donnell, Craig, Scott McDonald. Subs: Corr, Clarkson, Kevin McDonald, Kinniburgh, Wright.
Rangers: Klos, Hutton, Moore, Frank de Boer, Ball, Namouchi, Hughes, Rae, Vanoli, Thompson, Mols. Subs: Ross, McGregor, Walker, Adams, McDormack.
Referee: J Rowbotham