Napoli's 3-0 Serie A win over Pisa triggered a £38 million clause in Hojlund's contract, making the transfer a done deal.
In an emotional Instagram post, Hojlund expressed his gratitude to Manchester United fans, saying: "Goodbye to Manchester United is a difficult goodbye."
"My childhood dream came true by playing at Old Trafford in a red jersey," he wrote.
"The way you fans supported me, made me feel at home and helped me regain my confidence is something I'm thankful for."
"The goal I scored today symbolizes a new beginning, where I'll give my all to Napoli and thank Manchester United fans, players, and staff for making my childhood dream a reality."
"It's time for new goals, so let's chase them."
