Background: The validation of assessment instruments is of great importance when they are applied in clinical and healthcare settings, since their safe and reliable use is essential for the application of appropriate and high-quality treatments. The motor activity log (MAL-30) is an instrument widely used by professionals in the clinic, which has been validated in different countries, languages and populations. The aim of this study was to determine the reliability and validity of the MAL-30 scale for post-stroke patients in a Spanish sample. Methods: For this purpose, internal consistency tests were carried out using Cronbach’s alpha, item–item and item–total correlations, and a half-and-half test for reliability. For the validation, criterion validity tests were performed using the Fugl-Meyer assessment scale as the gold standard, and the convergent validity tests were carried out by correlation with the action research arm test (ARAT), box and block test (BBT), functional independence measure (FIM)–functional assessment measure (FAM), Lawton and Brody index and stroke quality of life scale (ECVI-38). Results: The results showed good internal consistency, as well as a good criterion and convergent validity. Conclusions: The MAL-30 instrument can be considered a valid and reliable tool for assessing the quantity and quality of the use of the affected upper limb in the performance of the activities of daily living and the instrumental activities of daily living after stroke in a Spanish sample.