| Timbun Mata Island | |
| Coordinates: | 4.6403°N 118.4747°W |
| Map: | Borneo |
| Location: | Darvel Bay |
| Archipelago: | Borneo |
| Waterbody: | Celebes Sea |
| Area Km2: | 130.7 |
| Length Km: | 26 |
| Width Km: | 10 |
| Coastline Km: | 79.9 |
| Elevation M: | 620 |
| Highest Mount: | Mount Tannabalu |
| Label Position: | right |
| Country: |  Malaysia |
| Country Admin Divisions Title: | State |
Timbun Mata Island (Malay: Pulau Timbun Mata) is the largest island on the south side of Darvel Bay, in Semporna, Sabah, Malaysia. It is over long and almost wide at the widest point. The island is mountainous and was formerly (pre-2000) densely wooded. Mt. Tannabalu, the highest point at, is a conical, extinct volcano located at the centre of the island. A secondary peak, Mt. Sedungal, at the east end of the island rises to . The south side of the island is only separated from the mainland by a shallow channel known as the Trusan Sigalong. It is located at 4.6403°N 118.4747°W with an area of .
The island has been inhabited since before records were kept. There are several villages on the island which have been there for at least several hundred years, Mantandak (in the west), Lakai Lakai (north), Dap Dap (northeast) and Kubor (east). In addition there are newer, illegal settlements which have sprung up on the southeastern portion of the island.
The island was declared a forest reserve in 1930, but had been planted in teak as early as the 1880s. The teak forests have been periodically surveyed, but inroads by illegal logging and land clearing has reduced them.