This study evaluated the existence of universal principles of cognition, common to language and arithmetic. Specifically, we analysed cross-domain semantic priming between affirmative sentences and additions, and between negative sentences and subtractions. To this end, we developed and tested a new priming procedure composed of prime sentences and target arithmetic operations. On each trial, participants had to read an affirmative or negative sentence (e.g., “The circle is red”, “The square is not yellow”) and select, between two images, the one that matched the meaning of the sentence. Afterwards, participants had to solve a one-digit addition or subtraction (e.g., 7 + 4, 6 – 3), either by selecting the correct result between two possible alternatives (Experiment 1), or by verbalizing the result of the operation (Experiment 2). We manipulated the task difficulty of both the sentences and the operations by varying the similarity between the response options for the sentence (Experiment 1 and 2), and the numerical distance between the possible results for the operation (Experiment 1). We found semantic priming for subtractions, so that participants solved subtractions faster after negative versus affirmative sentences, and this effect was modulated by the difficulty of the operation. This is the first study reporting semantic priming effects between language and arithmetic. The outcomes of this work seem to suggest a shared semantic system between both cognitive domains.