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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1. LONDON, ENGLAND - AUGUST 18: Kieran Trippier of Tottenham Hotspur celebrates after scoring his team's second goal during the Premier League match between Tottenham Hotspur and Fulham FC at Wembley Stadium on August 18, 2018 in London, United Kingdom. (Photo by Julian Finney/Getty Images)
Kieran Trippier of Tottenham Hotspur celebrates after scoring his team's second goal during the Premier League match between Tottenham Hotspur and Fulham FC at Wembley Stadium on August 18, 2018 in London, United Kingdom. (Photo by Julian Finney/Getty Images) Photo: Julian Finney
2. FA Youth Cup win at Manchester City
Trippier was part of the Manchester City side who won the FA Youth Cup in 2008. At 17, he started the match as City won 4-2 on aggregate against Chelsea at The City of Manchester Stadium. He picked up a late injury following a dangerous tackle from Chelsea's Jacob Mellis, who was shown a straight red card. Photo: Alex Livesey
3. Young player of the year at Barnsley
As a 19-year-old Trippier experienced his first taste of senior football on loan from Manchester City at Barnsley between 2010 and 2011. He made 42 Championship appearances for the South Yorkshire club, scoring twice. He was also named the club's player of the year in his only full season at Oakwell. Photo: GLYN KIRK
4. Burnley breakthrough
Eddie Howe signed Trippier for Burnley on loan from Manchester City during the 2011-12 season, a move that was made permanent midway through the campaign. Trippier has pointed to the decision to join Burnley as the turning point in his career as he was named as the club's player of the year in 2011-12 and was also named in the Championship team of the season. Photo: Clive Brunskill