Clethra pachyphylla is a tree in the family Clethraceae. The specific epithet ' is from the Greek meaning 'thick leaves'.
Clethra pachyphylla grows up to tall. The fissured bark is pale grey. The scented flowers are white. The roundish fruits measure up to in diameter.
Clethra pachyphylla is endemic to Malaysian Borneo. Its habitat is hill and montane forests from to altitude.