Many students suffer from motivational problems when doing homework. To investigate whether an intervention that effectively promoted value beliefs in mathematics promoted students’ homework motivation and behavior, we analyzed data from a cluster randomized controlled study with two classroom-based relevance interventions (writing a text or evaluating quotes from interviews) with 82 classrooms and 1,978 ninth-grade students. Students’ math-specific homework motivation and behavior were assessed with homework diaries over a period of 4 weeks after the intervention. Latent growth curve analyses revealed that students in the text condition reported higher triggered interest but also lower homework completion than students in the control condition in the first week after the intervention. Students in the quotations condition reported higher utility of homework for future life, and higher homework effort directly after the intervention. The study highlights the potential of classroom-based relevance interventions to foster homework-specific outcomes, when considering situational, behavior-related measures.