This question came about in a meeting I was at with a parish council. Nowhere is it referenced (in the Bible especially) that Mary was baptized. Although, She was sinless…so was Jesus and He had John the Baptist baptize Him. Thanks,
Baptism removes Original Sin. Mary was preserved from Original Sin (the Immaculate Conception) and therefore she had no need to be baptized.
St. Justin Martyr (d. 165) in his Dialogue with Trypho pointed out that the Jesus had no need to be baptized—just as he had no need to be born, to suffer, or die—but did so in order to reveal himself to humanity. It was at his baptism that the Holy Spirit revealed he is the Son of God.
Others have taught that Jesus was baptized so that his life might be an example for us to follow and revealed to us the sacrament of baptism. For in our baptisms grace flows from the water to us, but in the baptism of Christ grace flowed from him to the water.
Catechism of the Catholic Church:
536 The baptism of Jesus is on his part the acceptance and inauguration of his mission as God’s suffering Servant. He allows himself to be numbered among sinners; he is already “the Lamb of God, who takes away the sin of the world”. Already he is anticipating the “baptism” of his bloody death. Already he is coming to “fulfill all righteousness”, that is, he is submitting himself entirely to his Father’s will: out of love he consents to this baptism of death for the remission of our sins. The Father’s voice responds to the Son’s acceptance, proclaiming his entire delight in his Son. The Spirit whom Jesus possessed in fullness from his conception comes to “rest on him”. Jesus will be the source of the Spirit for all mankind. At his baptism “the heavens were opened” - the heavens that Adam’s sin had closed - and the waters were sanctified by the descent of Jesus and the Spirit, a prelude to the new creation.