Niemi made 22 saves in what was the 21st blanking of his five-year career, the last three having been spent with the Sharks.
San Jose's only other goal came shorthanded from Tommy Wingels 6:44 into the third.
The Sharks have won two straight and moved into a tie with St. Louis for the seventh and eighth post-season spots in the Western Conference. With 36 points, the Blues and Sharks have a two-point lead over Nashville and a three-point advantage over Dallas and Columbus.
All four goals were given up by Jonas Hiller on 29 shots.
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