Mature messenger RNA, often abbreviated as mature mRNA is a eukaryotic RNA transcript that has been spliced and processed and is ready for translation in the course of protein synthesis. Unlike the eukaryotic RNA immediately after transcription known as precursor messenger RNA, it consists exclusively of exons, with all introns removed.

Mature mRNA is also called "mature transcript", "mature RNA" or "mRNA".

The production of a mature mRNA molecule occurs in 3 steps:

1. During capping, a 7-methyguanosine residue is attached to the 5'-terminal end of the primary transcripts.
2. In polyadenylation , a poly-adenosine tail of about 200 adenylate residues is added by a nuclear polymerase post-transcriptionally.
3. RNA splicing removes the non-coding RNA introns leaving behind the coding sequences exons, which are then spliced and joined together to form the final mRNA.