This paper highlights phonological adaptation processes of the Swahili loanwords in the Ndali language. The study was conducted in Ileje District, in Songwe Region. The data were collected through the Ndali written texts, elicitation guides, and observation of native speakers’ oral conversations. The study was guided by the Optimality Theory (OT) which suggests that loanwords change to suit the phonotactic constraint of the native language. It was revealed that the Ndali language uses epenthesis and substitution as adaptation procedures for lexicons which are not well molded to influence them to fit in with the acquiring rules. More importantly, the findings revealed that with regard to borrowing, the Ndali language has changed its phonological structure by introducing new consonants and allowing consonant clusters. The study recommends further studies on phonological adaptation processes in other districts where the Ndali language is spoken as a native language such as Mbozi District and in other Bantu languages to come up with reasonable generalisations across languages. Other language levels including semantics, phonetics, morphology and pragmatics should be highly considered since the studies will act as the way of preserving African indigenous languages and will act as instrumental tools towards promoting ethnic community languages.