Genesis Rabbah (Hebrew: בְּרֵאשִׁית רַבָּה‎, B'reshith Rabba) is a religious text from Judaism's classical period, probably written between 300 and 500 CE with some later additions. It is a midrash comprising a collection of ancient rabbinical homiletical interpretations of the Book of Genesis (B'reshith in Hebrew).

It is expository midrash to the first book of the Torah, assigned by tradition to the amora Hoshaiah (or Osha'yah), who flourished in the third century in Roman Syria Palaestina. The midrash forms an aggadic commentary on Genesis, in keeping with the midrashic exegesis of that age. In a continuous sequence, broken only toward the end, the Biblical text is expounded, verse for verse, often word for word. Only genealogic passages and passages that furnish no material for exposition (as the reiterated account of Abraham's servant in Genesis 24:35–48) are omitted.