核糖核酸外切酶（Exoribonucleases）是核糖核酸（RNA）的外切酶，是一种能降解RNA，并在5'端或3'端的核苷酸移除的酶。能移除5'端核苷酸的这种酶称作「5'-3'核糖核酸外切酶」，而能移除3'端的则称作「3'-5'核糖核酸外切酶」。

此类酶有两种机理，分别是以水（水解活性）或以无机磷酸盐（磷酸解活性）去破坏RNA上的核苷酸-核苷酸键。水解核糖核酸外切酶分类在EC3.1中，因以水去降解RNA，因此生成单磷酸核苷；而以无机磷酸盐降解的则因有外在磷酸盐加在生成分子上，因此形成二磷酸核苷。

An exoribonuclease is an exonuclease ribonuclease, which are enzymes that degrade RNA by removing terminal nucleotides from either the 5' end or the 3' end of the RNA molecule. Enzymes that remove nucleotides from the 5' end are called 5'-3' exoribonucleases, and enzymes that remove nucleotides from the 3' end are called 3'-5' exoribonucleases.