It is now well established that reading words in a second language (L2) automatically activates native language (L1) translations in bilinguals. Although there is evidence that access to such representations is inhibited when words have a negative emotional valence, the mechanism underlying such inhibition is elusive, and it is unknown whether inhibition arises online as L2 is being processed or whether negative valence affects subsequent L1 processing. Here, we recorded event-related brain potentials in Chinese-English bilinguals engaged in an implicit translation-priming paradigm involving L2 (English) word pairs. Participants performed a semantic relatedness task, unaware that word pairs could conceal a sound repetition if translated into Chinese. When emotional valence was manipulated in prime position (first word), we observed form repetition priming through L1 translations for positive but not for negative words. However, when emotional valence was manipulated in target position (second word), priming occurred for both positive and negative word valences. This result begins to elucidate the mechanism by which emotion regulates language processing in bilinguals: Negative words in L2 induce a refractory period during which cross-language lexical access is blocked. These findings show that despite being neuroanatomically distinct in the human brain, emotional (limbic) regulation systems can penetrate language processing.