The Dynamo (6-7-3) took a 1-0 lead in the 11th minute and rode it into halftime when Nelson Quiñónes took a pass from Adalberto Carrasquilla and scored his first career goal. The 20-year-old was making his third career start.
Houston stretched its lead to 2-0 just five minutes into the second half on a penalty kick by Amine Bassi — his seventh goal this season.
Corey Baird subbed in and scored for the second time this season, taking a pass from Aliyu Ibrahim in the 69th minute and finding the net just six minutes after entering. Franco Escobar, who played for LAFC last season, used an assist from Héctor Herrera in the 89th minute to score his first goal for the Dynamo and complete the scoring.
Steve Clark saved two shots to earn his sixth clean sheet of the season for the Dynamo. It was the first clean sheet by either side in 11 all-time matchups. John McCarthy finished with one save for LAFC (7-2-5).
Houston beat LAFC 2-1 in August of last season after going 0-5-4 in the first nine meetings. The Dynamo improve to 6-1-1 at home this season.
LAFC has won just three of its last 13 matches in all competitions. The club has been blanked in three straight matches for the first time.
The two clubs square off again on Wednesday in Los Angeles.