The Pride of Burgundy, will sail only with freight and return in June as the firm vows to "take back market leadership" on the route.
The 28,000 ton vessel can carry up to 120 lorries.
David Stretch, chief executive of P&O Ferries, said: “I am delighted to welcome a fifth ship back to our Dover to Calais fleet which will increase flexibility for customers and enable us to deliver a cost effective freight service on the English Channel as the economy returns to normal.
"Dover to Calais is a vital trade route both for the UK and EU economies as well as the thousands of businesses which rely on our services and we aim to return our market share back to where it belongs.”
Mike Bhaskaran, chief operating officer, logistics and technology, of P&O's owners, DP World, added: “I would like to thank everyone at P&O Ferries who has worked hard to keep trade flowing during the last 12 months and am excited by the opportunities which the arrival of a fifth ship on Dover to Calais brings, both in terms of our offer to customers and also returning P&O to growth.”
Cross-Channel travel for freight has dipped as a result of both the pandemic and Brexit.
Last year P&O shed hundreds of staff as a result of the impact of the travel restrictions caused by Covid.