Fastjet's Tanzanian passenger revenues for June rose 22% from May's to reach £2.2 million ($3.3 million).
The African low-cost start-up's load factor in that market climbed from 68% to 78% over the same period.
In a trading update, Fastjet attributes the result partly to the reintroduction of the Kilimanjaro-Zanzibar route and "a change in the competitive environment in Tanzania".
Fastjet's Tanzanian operation carried its 200,000th passenger in June and the airline says it "expects this figure to grow by at least 28,000 by the end of July".
Having secured traffic rights to operate between Tanzania and South Africa in June, chief executive Ed Winter says he is now seeking to get landing slots and other final arrangements in place to get the routes on sale "as soon as possible".