The 18-year-old put pen to paper on Tuesday afternoon, formalising an agreement reached the previous Friday, after a breakout pre-season in which he emerged as Barcelona's top scorer with four goals in five matches, including a brace against Birmingham City.
His previous deal, signed when Barcelona exercised their buy option on him in June, carried a release clause of just €15 million, a figure the club moved quickly to protect once his rapid progress became clear.
Speaking after signing, Hamza described the moment as a dream come true, while acknowledging he still has plenty to prove before securing a regular role under Hansi Flick.
"It's a dream to renew with this club, to be here and represent Barça," he said. "I hope to improve every day, to keep working to keep growing. Playing time is the coach's decision. I need more time to keep improving. I know the minutes will come and I have to be ready to take advantage of them when they arrive."
Asked about competing for a place in a crowded forward line, Hamza was realistic about his path into the side.
"My goal is to score, like any striker. But there's Lamine, Gavi, Raphinha... My contribution would be to add goals and help the team," he said, adding that he would not consider a loan to Barcelona's reserve side beneath him. "I don't know if I'll play with the second team, I don't think I shouldn't do it, nor should I be ashamed if I do. What matters is getting minutes, scoring goals and proving it on the pitch, wherever that is - with the first team, the reserves, the national team."
Hamza also spoke of the confidence he draws from his standing in Egypt.
"It gives me a lot of confidence having so many people supporting me in my country. I think they're proud of me," he said, while praising the culture within Barcelona's dressing room. "The staff support me a lot and help me grow and improve. All my teammates have supported me from day one too. It's like a family, a place you want to go to when you wake up in the morning."
Hamza, nicknamed "the Haaland of the Nile" for his movement and finishing, said he could learn plenty from studying Erling Haaland's game, and named Lamine Yamal as the Barcelona teammate most deserving of this year's Ballon d'Or.
"There are many players in our dressing room who deserve it, but Lamine deserves it most. I'm looking forward to playing alongside him," he said, before reflecting on his own path to Camp Nou. "The first memory I have is a Champions League match against PSG. When they told me I would play for Barça, I can't express what I felt. It's something you have to live through, it's a feeling."