This study presents the design, development, and evaluation of a web-mobile alumni engagement platform for Moshi Co-operative University (MoCU). Recognising the critical role of alumni in supporting institutional growth and fostering lifelong academic relationships, the research aimed to create an inclusive, user-centred digital solution to enhance interaction, track alumni progress, and improve institutional communication. A mixed-methods approach was employed, involving a pre-implementation questionnaire to gather requirements from 100 purposively selected alumni and post-implementation surveys to assess usability, adoption, and satisfaction. System development followed a User-Centred Design (UCD) framework integrated with iterative prototyping and stakeholder feedback loops. The platform featured tools such as alumni directories, job boards, mentorship channels, and event alerts, deployed on mobile and web channels to maximise accessibility. Results indicated strong platform adoption (75% frequent usage), high satisfaction (over 70% satisfied), and alignment between pre-identified alumni needs and implemented features. The system demonstrates the potential for ICT solutions to bridge alumni-institution gaps, especially in resource-constrained contexts. The study concludes with recommendations for sustainable engagement, scalability, and continuous system evaluation.