The 31-year-old right-back is the first signing of the PIF ownership era as he joins for a reported £12million fee plus add-ons.
Signing a La Liga winner and England international will be seen as a big coup for Newcastle, who currently sit 19th in the Premier League table.
Trippier has enjoyed an impressive career in England, Spain and at international level and will be looking to make a mark on Tyneside to help The Magpies keep their top flight status intact.
He will wear the number 15 shirt for Newcastle and could be part of the squad that faces Cambridge United in the FA Cup third round at St James’s Park on Saturday (3pm kick-off).
Following Trippier’s arrival at Newcastle, we’ve looked at his career so far and picked out 10 key moments, some of which have have helped him establish himself as one of world football’s best right-backs.
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9. 2020-21 La Liga Champion
Trippier left the Premier League in 2019 to join Atletico Madrid. He quickly established himself in Spain and won the first major trophy of his career last season as Atletico clinched the La Liga title ahead of Real Madrid and Barcelona. He started 28 matches for Diego Simeone's side and registered six assists from right-back that season, becoming the first Englishman to win a La Liga title since David Beckham. Photo: Angel Martinez
10. Euro 2020
Trippier shone again on the international stage last summer as England reached the Euro 2020 final, their best ever performance in the competition. The 31-year-old featured in five matches for England and assisted Luke Shaw's early goal in the final against Italy. Photo: FACUNDO ARRIZABALAGA
11. Signing for Newcastle United
Leaving a side competing at the top of La Liga and in the Champions League for a club sitting 19th in the Premier League is a bold career move for Trippier but the lure of returning to England and being part of a new project on Tyneside has proven too strong to resist. Whether it's a successful move or not remains to be seen but the decision to return to the Premier League will prove to be a key moment in his career. Photo: Alex Morton