With seven wins and a draw in a nine-game contest which had 28 contestants, the 18-year-old reached the desired 7.5 points to take the glory.
However, it was his win over candidate master Chiletso Chipanga in the seventh game that gave Mwale the confidence of retaining the title that came with a K20 000 (about $120) prize and a trophy.
Before that game, Chipanga, who was second with seven points, was floating with six straight victories while Mwale was a point behind.
But Chipangaâ€™s subsequent loss to South Africa-based Richard Mbedza, who took the third slot with 6.5 points, gave Mwale the joy at the end of the four-day event.
“It has been a while since someone defended a chess title in the country and it feels like a dream that I have managed to break the jinx,” marvelled Mwale.
Mwale will now lead his elder brother Chuma, Chipanga, Mbedza and Joseph Nyambalo to the World Chess Olympiad in Turkey in the menâ€™s category. The female section will comprise Linda Jambo, Vitumbiko Gondwe, Ellen Mpinganjira, Wezzie Mzia and Judith Phiri.