Watched by a 40,000 crowd, Gardner's strike was one of the few clear-cut incidents in a game which often lacked a cutting edge from both sides.
West Ham slumped to their third successive league defeat and, despite some substitutions by manager, Alan Curbishley, the Hammers failed to find a way through Villa's defence.
It was obvious that once they had taken a first-half lead, Villa were intent on maintaining their advantage and in so doing avoiding a similar collapse to that which occurred at Tottenham on Monday when they were leading 4-1 at one stage.
Overall it was a well-merited success achieved without hitting too many high notes against a West Ham side which lacked the sparkle to end their recent poor run.
There was a crucial incident in the 13th minute when the elusive Ashley Young outpaced Lucas Neill only for the West Ham skipper to tug the youngster's shirt in the penalty area. Referee Steve Tanner, however, failed to spot the infringement and West Ham were let off the hook.
Following a lot of cut and thrust play from both teams Villa stormed into a 24th minute lead.
Matt Upson impeded Gabby Agbonlahor on the edge of the penalty area, Gardner took the free-kick, and as the West Ham defenders jumped up, the ball whistled low into the net for the young Villa player's second goal of the week.
West Ham's neat approach work was generally good but the end product was way below their expected standard.
Their only reply was a weak header from Freddie Ljungberg, who began brightly but then faded against the strong-tackling Wilfred Bouma.
It was significant that Dean Ashton was unable to make much of an impact. He was effectively shut out of the game by another impressive performance from Martin Laursen.
Carlton Cole, who took over from Henri Camara in the first half, possibly had West Ham's best opportunity to equalise ten minutes into the second half but the Hammers striker, who had a shot spell on loan with Villa, failed miserably to get enough power behind his effort to beat Scott Carson.
At this stage Villa were sucked into a survival battle as West Ham made more of their attacking options with Lee Bowyer rising the tempo.
As Villa dropped further back on to the defensive Cole had another effort but it was just off target.