Newcastle smashed their transfer record on Friday with a reported £58 million swoop for Real Sociedad's Sweden striker Alexander Isak.
Isak, 22, agreed a "long-term" contract with the Premier League club and could make his debut in Sunday's match at Wolves.
The towering 6ft 4in targetman scored 44 goals in 132 appearances for LaLiga side Sociedad and has netted nine times in 37 international appearances for Sweden.
Isak, who has also had a spell with Borussia Dortmund, is Newcastle's fourth signing since the end of last season following the arrivals of Matt Targett, Nick Pope and Sven Botman.
"I'm delighted to have it done. It was a big, big decision for me but it is a decision I am really happy with," Isak said.
"It is a great, historical club that I think anyone would like to play for, with amazing fans. They were a big part of why I came here and also the club's project, which is one that I really believe in.
"You always want to go into a team and know how they play. Newcastle play very attractive football and I want to be a part of that."
Newcastle boss Eddie Howe had been looking for attacking reinforcements after striker Callum Wilson suffered a hamstring injury which is likely to sideline him for several weeks.
Isak's signing is the latest indication of Newcastle's ability to flex their financial muscle thanks to their Saudi-based owners, who took over at St James' Park last year.
"I'm very excited that Alexander has chosen to join us. He is an outstanding talent who is capable of making a big contribution to the team," Howe said.
"He is technically very good, with a mix of attributes that will complement us, but he is also at a great age to grow with this club.
"I want to thank the club's owners and transfer committee for bringing Alexander to Newcastle. We are all delighted to have him on board."