The Right Reverend Justin Welby said he "very cheekily" asked Pope Francis to record a video message for Thy Kingdom Come, the international prayer campaign which has won support from a range of Christian denominations.
The Archbishop says the Pope's spontaneous reaction was "utterly inspiring".
In his message, Pope Francis says the Lord's Prayer helps Christians to ask the Holy Spirit to fill their hearts.
"We all have a problem and that is our hearts tend to shrink, become smaller and close.
"We can't solve that problem by ourselves. Only the Holy Spirit can solve it."
Justin Welby used Twitter to ask people to share the Pope's video message, which implicitly endorses Thy Kingdom Come.
Please watch and share this beautiful message from Pope Francis. Praise God that @thykingdom_come is becoming a global movement of love and hope that's uniting us around Jesus Christ. #ComeHolySpirit! pic.twitter.com/wB6GRB7rnY
— Archbishop of Canterbury (@JustinWelby) May 19, 2019
Video of the meeting shows the Pope and the Archbishop in animated conversation. Pope Francis gestures with his hands to underline the message that Christians depend on the Holy Spirit to find the strength to face life's challenges.
The Pope concludes his video message, "With my brother Justin Welby, we want to tell you that we walk alongside you in this prayer - Thy Kingdom Come."
Part of Thy Kingdom Come's activities are a global wave of prayer which runs from May 30th to June 9th.
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