Abstract Research and development (R&D) investments foster green innovation, which is key to decarbonize the energy system and attain long-term climate goals. In this paper, we link three integrated assessment models that possess a macroeconomic framework – WITCH, MERGE-ETL and GEM-E3 – with the bottom-up technology-rich energy system model TIAM-ECN, in order to quantitatively explore how investments in R&D can support deep decarbonization pathways. We take advantage of the endogenous technological learning feature of the first three models to derive R&D-induced capital cost reductions for strategic clusters of low-carbon technologies: solar energy, on- and offshore wind energy, carbon capture and storage, advanced fuels, and batteries for electric vehicles. We examine scenarios with different assumptions on CO2 mitigation and R&D policy. These assumptions are harmonized among our four models, and capital cost reductions driven by R&D are exogenously incorporated in TIAM-ECN, which enables a detailed assessment of the required energy transition. Our results show that the stringency of climate change mitigation policy remains the key factor influencing the diffusion of low-carbon technologies, while R&D can support mitigation goals and influence the contribution of different types of technologies. If implemented effectively and without worldwide barriers to knowledge spill-overs, R&D facilitates the deployment of mature technologies such as solar, wind, and electric vehicles, and enables lower overall energy system costs.