Malick was born in Düsseldorf, Germany on 8 August, 2001 to a Senegalese father and a Finnish mother and began playing football for his local team, TV Kalkum-Wittlaer, before playing for Fortuna Düsseldorf, Bayer Leverkusen and Borussia Mönchengladbach's youth teams.
The German defender joined FC Schalke 04 as a 14-year-old and after progressing through one of Germany's most prestigious football academies, which has produced the likes of Manuel Neuer, Mesut Özil and Leroy Sané, he made his Bundesliga debut in March 2020 before making a further three league outings during the 2019/20 campaign.
Despite a breakthrough season in 2020/21, scoring on his full home debut in a 1-1 draw against Stuttgart, Thiaw suffered relegation with Schalke after the club finished at the foot of the Bundesliga but they returned to the German top-flight at the first time of asking after winning the 2. Bundesliga title the following season, with the centre-back recording ten league clean sheets in 31 league matches.
Three weeks after his 21st birthday, Thiaw joined Italian giants AC Milan for a reported £6 million and made 24 competitive appearances for the Serie A side during his maiden season at the San Siro as well as featuring in their run to the 2022/23 Champions League semi-finals alongside Sandro Tonali, who would join the Magpies the following summer.
Thiaw notably impressed in both legs of Milan's Round of 16 win against Tottenham Hotspur, keeping clean sheets in respective games against the North London outfit as well as winning the Man of the Match award.
Thiaw featured on the opposing side for Newcastle United's first UEFA Champions League fixture in two decades as the tall centre-back kept a clean sheet during the Magpies' goalless draw against Milan at the San Siro in September 2023.
After suffering a hamstring injury during the end of the calendar year, Malick played 30 games in all competitions as I Rossoneri finished as Serie A runners-up as well as reaching the Europa League quarter-finals.
Malick has gained 11 caps for Germany at under-21 level, grabbing a goal and assist on his debut in a 3-1 win against Lativa in September 2021.
A member of his country's squad which won the European Under-21 Championship in 2021, Thiaw was handed his senior international bow by Hansi Flick at the age of 21, starting in a friendly against Poland in June 2023 before gaining a further two appearances for the four-time World champions.
After plying his trade in Germany and Italy, the Magpies' third senior signing of the summer will be aiming to make a strong impression in English football and will be aiming to make his Premier League bow in United's trip to Aston Villa on Saturday afternoon (kick-off 12.30pm BST).
The 24-year-old added: ""I'm still very young so, in general, there's a lot of stuff to do. I know I can learn a lot and I am really open to learn a lot.
"I feel ready. I've already had a good pre-season with AC Milan so, physically, I'm ready. I came here with some ambitions and I know Newcastle is an ambitious club as well.
"First of all, I want to play as many games as possible and help the team to do (well) in the present and also in the future."
