Shiels' future has been the subject of debate but a goal in each half ensured Rangers took all three points in front of a little over 42,00 fans at Ibrox.
The home side made a blistering start to the game with Andy Little having an effort cleared off the line after just four minutes.
It was a sign of things to come as Shiels - making a return to the starting line-up - opened the scoring for Rangers from the resulting corner, firing in low and hard past Greg Paterson.
Little almost extended Rangers' lead with a half-volley midway through the opening period but his effort went narrowly over the bar.
Moments later Fraser Aird linked well with Bilel Mohsni and fired a near-post shot towards goal that needed Paterson's intervention.
East Fife should have got back on level terms through Liam Buchanan but his first shot was blocked by Mohsni and his rebound hit the side-netting.
Nicky Law then made a last-ditch tackle to deny Buchanan again as Rangers took a one goal lead into the break.
Buchanan had another chance for the visitors in the second half after some nervy defending from Rangers but his shot was wide of the post. Moments later Gary Fisher was denied by Rangers keeper Cammy Bell.
But the home side made the game safe midway through the second half when Sebastien Faure found Little in the penalty area. He laid the ball off to Shiels who made no mistake with a thunderous strike past Paterson.