The present study investigates the rhythmic properties of the non-native speech produced by multilingual learners with Mandarin Chinese as a heritage language who acquire French as foreign languages in the German school context. Data collected from monolingual German and monolingual Chinese learners serve as control materials. Regarding the production of the syllable-timed speech rhythm of French, it is shown that monolingual learners with (syllable-timed) Mandarin Chinese as L1 perform more target-like than learners with (stress-timed) German as L1. The multilingual learners with Mandarin Chinese as a heritage language obtain intermediate values, depending on extra-linguistic factors such as attitudes and multilingual and phonological awareness. They are thus advantaged over the German monolinguals regarding the learning of French in that the speech rhythm of their heritage language Mandarin Chinese may be positively transferred to the foreign language. This suggests that multilingual and phonological awareness should be promoted in contexts of foreign language learning in both learners and teachers.