As one of the main knowledge producers, researchers can play an important role in contributing to efforts that bridge the gap between knowledge, policy and practice. However, for researchers to play this role, they need knowledge translation (KT) capacities that many typically lack. Furthermore, research has confirmed that little is known on KT training approaches for LMICs researchers and their effectiveness. This paper seeks to contribute to filling this knowledge gap on KT training approaches for LMIC researchers by assessing the effectiveness of a training and mentorship intervention to build African researchers' KT capacity. We conducted KT training and mentorship for 23 early and mid-career researchers from 20 universities in sub-Saharan Africa. This comprised a 5-day intense residential training workshop, followed by a 6-months mentorship. A pre- and post-training test was used to assess the immediate effect of the workshop. The intermediate effect of the training following a 6-month mentorship was assessed by the number of researchers who completed policy briefs during this period and those who participated in the webinar series conducted during this period. Overall, the aggregate average point change in the self-reported learning between the pre-training and the post-training survey was 1.9, which demonstrated the effectiveness of the training workshop. This was confirmed by a 33.7% increase in the aggregate average percentage of participants that responded correctly to questions assessing topics covered in the training between the pre-training and the post-training survey. During the mentorship period, 19 of the 23 researchers prepared and submitted complete drafts of their policy briefs within two months after the training. Fewer (4) researchers revised and submitted final policy briefs. More than half of the trained researchers participated in the webinars conducted in the first three months of the mentorship, whereas less than half of the researchers participated in the webinars conducted in the last three months. KT training and mentorship can be an effective intervention for addressing researchers' KT capacity gaps. For sustainability, KT training and mentorship need to be integrated in graduate training programmes in universities so that future LMIC researchers leave training institutions with the KT capacities they need for influencing policy and programme decisions and actions.