The Solomon Islands in Melanesian region of South Pacific lie in an equatorial climate and harbour diverse habitats covered by forests. Based on field surveys and specimens examination, six Begonia species were confirmed from the Solomon Islands, and a key of the species is provided for identification. Besides the two widespread species, B. somervillei Hemsl. and B. weigallii Hemsl., four new species, B. choiseulensis, B. occulta, B. phycoduroides and B. rubroflabellata, are described and illustrated. All species belong to sect. Petermannia, and five are endemic to the Solomon Islands. Their conservation status following IUCN criteria are also assessed.