The service, held to mark the surrender of Japan at the end of World War Two, was led by Reverend Canon Bob White.
The event included readings from Burma veterans and a performance from the Portsmouth Military Wives Choir.
The service saw wreaths laid at the war memorial, including one on behalf of the city placed by the Lord Mayor of Portsmouth, councillor Frank Jonas.
Council leader Donna Jones said: "It's important for communities to commemorate events such as these.
"The ceremonies in the city provide a poignant opportunity to reflect and remember."
A special VJ Day Choral Evensong was due to take place from 18:00 BST at Portsmouth Cathedral on Sunday.
Veterans and soldiers attended a ceremony at Portsmouth's cenotaph to mark the 70th anniversary of VJ Day.