The defender, who rose through the youth system at Reading, made his name in the Championship with Barnsley, before he earned himself a move to Swansea two years ago.
Some impressive performances last season earned him a call-up to Gareth Southgate's senior squad for two friendlies in March although he did not feature.
The 24-year-old is certainly highly rated and was left relatively unscathed by Swansea's disastrous campaign in 2017/18. But how can he help keep Fulham in the Premier League this time around?
First off, Mawson is a ball playing defender. Ball playing defenders are the sought-after defender nowadays, with the majority of teams playing out from the back. Over his two-year spell at Swansea, Mawson was part of a system in which defenders were the players that started the attacks. The centre-half averaged over 45 passes per match, and has completed 353 accurate long balls in the Premier League.
As well as being able to play with the ball at his feet, Mawson is a combative defender. The England Under-21 international made 61 tackles in the Premier League over his time at Swansea, with a 74% tackle success rate. In terms of aerial duels the 6ft 2in defender won 206 battles alongside making 391 clearances and 357 recoveries.
Mawson's discipline during games is also something to highlight. The defender committed 29 fouls and only received four yellow cards, with no red cards to his name. At his young age Mawson seemingly has a level head and is able to adapt his game to whatever the game throws up. He only made two errors leading to goals over his Swansea tenure, which is an impressive stat.
Mawson is a goal threat from set pieces. As seen demonstrated by England at this year's World Cup, set pieces are a goldmine if you get them right.
With Mawson's height it allows him to attack the ball with conviction. He is not afraid to put his head in where it could hurt. Three headed goals and three goals scored with his right foot gives him options in different situations. Flick ons are also an important part of set pieces and if Mawson can get ahead of his marker there is no reason why he could set up chances.
Mawson's Premier League experience will undoubtedly come in handy when at Fulham. The Cottagers squad currently has only a handful of players that have had previous spells in the English top flight. Only Tim Ream, Andre Schurrle and new signing Aleksander Mitrovic in the squad have played at the level before, by adding Mawson you have a player who can help those without experience settle.
Mawson made a total of 65 appearances for Swansea over two seasons and was an ever-present in the Swansea starting line-up all last season, playing alongside the experienced Federico Fernandez and Leon Britton as he learned the game.
Mawson is set to continue his Premier League journey in west London and once the signing gets confirmed, Fulham will have one hell of a defender on their hands and it could well be the difference in staying up and going back down again.