After two straight one-sided setbacks, the 49ers took advantage of the struggling Rams while dominating the game on the ground. San Francisco improved to 2-2 while the Rams fell to 1-3 with their third straight loss.
Gore had averaged a modest 47 yards a game in San Francisco's first three contests, but he picked up seven yards per carry on Thursday. His night was highlighted by a 34-yard scoring run with 37 seconds left before halftime that finished off an 80-yard drive and gave the 49ers a 14-3 lead.
With the running game working so well, San Francisco quarterback Colin Kaepernick threw just 23 passes, completing 15 for 167 yards and two touchdowns.
San Francisco's other touchdowns came on fourth quarter runs of 1 yard run by Anthony Dixon and 29 yards by Kendall Hunter.
The 49ers piled up 219 yards on the ground to just 18 for the Rams. St. Louis quarterback Sam Bradford went 19-of-41 for 202 yards, a touchdown and an interception.