The lemon-bellied flyrobin or lemon-bellied flycatcher (Microeca flavigaster) is a species of bird in the family Petroicidae. Found in Australia, Indonesia, and Papua New Guinea, its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical mangrove forests.
The adult lemon-bellied flyrobin is around 11.5 cm long. The sexes have similar plumage. The nominate subspecies flavigaster has lemon yellow underparts, a white throat, grey face with a white eyebrow stripe, and olive-brown upperparts. Subspecies tormenti has white underparts, more greyish upperparts, has a longer bill and tail and is larger overall. Subspecies flavissima resembles flavigaster but has a more obvious yellow tinge to the upperparts, throat, yellow eyebrow and a shorter tail, while laetissima more closely resembles flavigaster, but has a shorter tail and bill and is larger overall.