Background This report evaluates the outcomes and effectiveness of the DTA3/COFUND doctoral fellowship programme, which ran from 2019 to 2023. Funded by the Horizon 2020 Marie Skłodowska-Curie PhD Fellowship programme, DTA3 aimed to foster interdisciplinary, international, and industry-focused research across 15 UK universities. Methods The programme supported 71 international fellows from diverse countries, emphasising inter-sectoral skills and post-doctorate employability. A mixed-methods study design was employed, involving online surveys, focus groups, and interviews with fellows, supervisors, and university programme leads. Results Key areas of evaluation included research activities, employment outcomes, wellbeing, doctoral training experiences, and institutional impact. The data revealed that 72% of fellows had submitted their PhD theses, with 66% having completed their viva by the report's conclusion. The programme also recorded a high employment rate, with 55% of fellows in the final stages of their PhD already employed. The DTA3 programme featured an enhanced training component, including annual summer schools, spring refresh events, autumn schools, and residential writing retreats. These events focused on enhancing employability, academic skills, research impact, and intersectoral collaboration. Despite challenges such as visa complications, COVID-19 restrictions, and international supervisor movements, the programme maintained a strong completion rate. Conclusions The report highlights the programme's success in providing fellows with significant international mobility opportunities, with many securing employment in their home countries or abroad shortly after completing their PhD. The DTA3 legacy includes ongoing cohort tracking, an alum network, and a dedicated legacy fund to support further international collaboration and knowledge exchange. Overall, the DTA3/COFUND programme demonstrated substantial impact in training and developing skilled researchers, promoting international collaboration, and enhancing employability in diverse sectors, thereby contributing positively to the global research community.