A Nigerian tourist, Ezihe Collins, 35, was captured on Sunday as he was driving a motorcycle from his house on Koh Phangan.
Koh Phangan police chief Sathit Kongnium said his passport had expired on Sept 28 last year. Authorities did not mention his visa stamp.
Pol Col Sathit said a search of his house on Sunday uncovered six bags of cocaine weighing almost 10 grammes. In a further inspection on Monday, authorities seized two books containing lists of names, believed to be his customers, and 34,000 baht in cash.