This is the traditional Catholic prayer to one’s guardian angel:
Angel of God, my guardian dear to whom God’s love commits me here. Ever this day/night be at my side to light, to guard, to rule and guide. Amen.
Whether guardian angels attend each and every person is not consistently believed or upheld by the Church Fathers in Christian thought, and hence is not an “article of faith”, although the concept is clearly seen in both the Old and New Testaments. According to St. Jerome the concept is in the “mind of the Church” and he stated that: “how great the dignity of the soul, since each one has from his birth an angel commissioned to guard it.”
Centuries later, in his 1997 Regina Caeli address, Pope John Paul II referred to the concept of guardian angel twice, and concluded the address with the statement: “Let us invoke the Queen of angels and saints, that she may grant us, supported by our guardian angels, to be authentic witnesses to the Lord’s paschal mystery“.