Information from: https://yearofstjoseph.org/devotions/prayers/
The official prayer of the Year of St. Joseph—To you, O blessed Joseph (Ad te, beate Ioseph)—was composed by Pope Leo XIII in his 1889 encyclical, Quamquam Pluries. The Holy Father asked that it be added to the end of the Rosary especially during October, the month of the Holy Rosary. This prayer is enriched with a partial indulgence (Source: USCCB).
THE YEAR OF ST. JOSEPH PRAYER
To you, O blessed Joseph (Ad te, beate Ioseph)
To you, O blessed Joseph, do we come in our afflictions, and having implored the help of your most holy Spouse, we confidently invoke your patronage also.
Through that charity which bound you to the Immaculate Virgin Mother of God and through the paternal love with which you embraced the Child Jesus, we humbly beg you graciously to regard the inheritance which Jesus Christ has purchased by his Blood, and with your power and strength to aid us in our necessities.
O most watchful guardian of the Holy Family, defend the chosen children of Jesus Christ; O most loving father, ward off from us every contagion of error and corrupting influence; O our most mighty protector, be kind to us and from heaven assist us in our struggle with the power of darkness.
As once you rescued the Child Jesus from deadly peril, so now protect God’s Holy Church from the snares of the enemy and from all adversity; shield, too, each one of us by your constant protection, so that, supported by your example and your aid, we may be able to live piously, to die in holiness, and to obtain eternal happiness in heaven. Amen.
“I do not remember even now that I have ever asked anything of [St. Joseph] which he has failed to grant… To other saints the Lord seems to have given grace to succour us in some of our necessities, but of this glorious saint my experience is that he succours us in them all…” (Autobiography of St. Teresa of Avila)