The Divine Mercy Chaplet is a relatively recent but very popular devotion revealed by Our Lord to St. Maria Faustina Kowalska, a Polish nun. On Good Friday 1937, Christ appeared to Saint Faustina and asked her to recite this chaplet for nine days, starting on Good Friday and ending on the Octave of Easter (the Sunday after Easter Sunday), now known as Divine Mercy Sunday.
The chaplet is most often recited during those nine days, but it can be prayed at any time of the year, and Saint Maria Faustina recited it almost unceasingly. A standard rosary can be used to recite the chaplet, and the entire devotion takes just 20 minutes—about the time it takes to pray the rosary.

1. Make the Sign of the Cross
2. Pray the Opening Prayers

There are two opening prayers; the second is repeated three times:

First Prayer
You expired, Jesus, but the source of life gushed forth for souls, and the ocean of mercy opened up for the whole world. O Fount of Life, unfathomable Divine Mercy, envelop the whole world and empty Yourself out upon us.

Second Prayer
O Blood and Water, which gushed forth from the Heart of Jesus as a fount of mercy for us, I trust in You! (repeat three times)

3. Pray the Our Father
4. Pray the Hail Mary
5. Say the Apostles' Creed
6. Pray the Prayer "Eternal Father"

On the Our Father bead before each decade, pray the following prayer:

Eternal Father
Eternal Father, I offer You the Body and Blood, Soul and Divinity of Your dearly beloved Son, Our Lord Jesus Christ, in atonement for our sins and those of the whole world. Amen.

7. Pray the Prayer "For the Sake of His Sorrowful Passion" Ten Times

On each of the Hail Mary beads in each decade, pray the following prayer:

For the Sake of His Sorrowful Passion

For the sake of His sorrowful Passion, have mercy on us and on the whole world.

8. Repeat Steps 6 and 7

On each of the next four decades of the Chaplet, repeat steps 6 and 7 (pray the "Eternal Father," followed by ten "For the Sake of His Sorrowful Passion").

9. Pray the Concluding Doxology Three Times

After you have prayed all five decades of the Chaplet, pray the following prayer, which is repeated three times:

Holy God, Holy Mighty One, Holy Immortal One, have mercy on us and on the whole world." (repeat three times)

10. Pray the Closing Prayer

After the doxology, pray the following final prayer:

Eternal God, in Whom mercy is endless, and the treasury of compassion inexhaustible, look kindly upon us, and increase Your mercy in us, that in difficult moments, we might not despair, nor become despondent, but with great confidence, submit ourselves to Your holy will, which is Love and Mercy Itself. Amen.

11. End With the Sign of the Cross