BACKGROUND: Improving global maternal, newborn, child and adolescent health (MNCAH) is a top development priority in Canada, as shown by the $6.35 billion in pledges toward the Muskoka Initiative since 2010. To guide Canadian research investments, we aimed to systematically identify a set of implementation research priorities for MNCAH in low- and middle-income countries. METHODS: We adapted the Child Health and Nutrition Research Initiative method. We scanned the Child Health and Nutrition Research Initiative literature and extracted research questions pertaining to delivery of interventions, inviting Canadian experts on MNCAH to generate additional questions. The experts scored a combined list of 97 questions against 5 criteria: answerability, feasibility, deliverability, impact and effect on equity. These questions were ranked using a research priority score, and the average expert agreement score was calculated for each question. RESULTS: The overall research priority score ranged from 40.14 to 89.25, with a median of 71.84. The average expert agreement scores ranged from 0.51 to 0.82, with a median of 0.64. Highly-ranked research questions varied across the life course and focused on improving detection and care-seeking for childhood illnesses, overcoming barriers to intervention uptake and delivery, effectively implementing human resources and mobile technology, and increasing coverage among at-risk populations. Children were the most represented target population and most questions pertained to interventions delivered at the household or community level. INTERPRETATION: Investing in implementation research is critical to achieving the Sustainable Development Goal of ensuring health and well-being for all. The proposed research agenda is expected to drive action and Canadian research investments to improve MNCAH.