The DNA of Trigonopterus specimens from the Sundaland region stored between ten and 32 years in museums could be used for next-generation sequencing. The availability of their cox1 sequence allowed the description of the following nine new species: Trigonopterusgrimmi sp. nov., T.johorensis sp. nov., T.lambirensis sp. nov., T.linauensis sp. nov., T.microreticulatus Riedel, Trnka & Wahab sp. nov., T.mulensis sp. nov., T.sarawakensis sp. nov., T.siamensis sp. nov., and T.singaporensis sp. nov. The alternative original spelling of the name T.tounensis Narakusumo & Riedel is chosen to prevail over T.tounaensis Narakusumo & Riedel. The new species represent the first country records of Trigonopterus for Brunei, Singapore, and Thailand. Thus, the genus´ known area of distribution in the Sundaland region is significantly extended. A key and a catalogue are provided to the Trigonopterus species from Borneo, W-Malaysia, Singapore, and Thailand.