OsRRMh, a homologue of OsRRM, encodes a Spen-like protein, and is composed of two N-terminal RNA recognition motifs (RRM) and one C-terminal Spen paralogue and an orthologue C-terminal domain (SPOC). The gene has been found to be constitutively expressed in the root, stem, leaf, spikelet, and immature seed, and alternative splicing patterns were confirmed in different tissues, which may indicate diverse functions for OsRRMh. The OsRRMh dsRNAi lines exhibited late-flowering and a larger panicle phenotype. When full-length OsRRMh and/or its SPOC domain were overexpressed, the fertility rate and number of spikelets per panicle were both markedly reduced. Also, overexpression of OsRRMh in the Arabidopsis fpa mutant did not restore the normal flowering time, and it delayed flowering in Col plants. Therefore, we propose that OsRRMh may confer one of its functions in the vegetative-to-reproductive transition in rice (Oryza sativa L. subsp. japonica cv. Zhonghua No. 11 (ZH11)).