This article examines the Cameroon-Nigeria and Eswatini-South Africa border disputes from a comparative perspective within the framework of the doctrine of uti possidetis juris in customary international law. Extant scholarly works on these two border disputes have not been sufficiently cogent to enable an evaluation of the relevance and shortcomings of uti possidetis juris. The study methodology is qualitative and includes archival and newspaper sources, in-depth interviews and focus group discussions. This study reveals that the strict application of the uti possidetis juris doctrine to the Cameroon-Nigeria dispute over Bakassi was inappropriate and did not generate the anticipated peace and security. The Eswatini-South Africa bilateral talks, aimed at adjusting colonially inherited borders, were an attempt to comply with uti possidetis juris, but flopped. Following the Cameroon example, the Eswatini monarchy then contemplated taking South Africa to the International Court of Justice (ICJ). But the two scenarios were different, and the invocation of uti possidetis juris was not an appropriate instrument for resolving the Eswatini- South Africa border dispute. Eswatini irredentism has persisted because of the country’s commitment to Sobhuza’s testament, which sanctioned the unity of the Eswatini people.