The phyline plant bugs belonging to the tribe Phylini in Thailand are reviewed. Sixteen species in eight genera that have hitherto been recognized are further documented. Nine species are described as new: Atractotomoidea izyaslavi, Decomia nigrissima, D. schuhi, D. taksini, Decomioides kazutakai, D. verecundus, Malaysiamiris rufobadius, Moissonia sakaerat, and Psallus buddha. Decomioides schneirlai Schuh is reported from Indochina for the first time and diagnosed. In addition, the following six new species, confirmed during examinations of related materials from the tropical and subtropical Asia, are described: Atractotomoidea insulicola (from Ryukyus, Japan), Decomia panayensis (Visayas, Philippines), Moissonia larutensis (Peninsular Malaysia), M. pardalis (Peninsular Malaysia), M. takaii (Ryukyus, Japan) and Opuna schwartzi (Peninsular Malaysia). Decomia cephalotes Poppius known only by a single male from Taiwan is recorded from the Ryukyus and diagnosed. Male and female genitalic structures are described and figured for most species. Biology and immature forms are reported in detail for Decomioides verecundus, Moissonia importunitas and M. takaii.