The 19-year old attacking midfielder joined the Eagles after bagging seven goals and 12 assists in 46 appearances for Reading.
Here are five things you need to know about this up-and-coming star.
OH, BROTHER!
Michael Olise's sibling Richard is also a footballer, representing England at youth level.
Following his older brother's footsteps, Richard also started his journey in the Chelsea academy and more recently has signed his first professional contract with the Blues.
INTERNATIONAL OPTIONS
Olise was born in England to a Nigerian father and French-Algerian mother, making him instantly eligible to represent England, Nigeria, France and Algeria internationally. Options!
The midfielder was called up to the France U18 for the 2019 Toulon Tournament and made his debut in June 2019 against Qatar U23.
Olise was also named as a standby for the Nigeria squad taking part in their Africa Cup of Nations qualifiers against Benin and Lesotho.
With four nations possibly vying for his loyalty, Olise is on the fast-track to becoming a fully-fledged international.
IMPRESSING THE GAFFER
As well as playing as an attacking midfielder Olise has also mastered the positions of centre midfield and winger.
And Crystal Palace boss Patrick Vieira is full of praise for his new signing, he said: "I think we are all really excited with his talent.
"He is working well and hard and in a good football club where we support him to improve himself.
"He is doing well in training, he can score goals and he showed that. He will be a really important player for us."
FASHIONISTA
Olise is proving himself in the world of football but he also is thriving on social media, especially as he portrays as a model in a few of his posts!
On Instagram, Olise can be seen posing in a bomber jacket with two Eagles on either side - it seems like he is representing his club.
In another post, the young midfielder is rocking a J'adior cap as he takes part in a photo-shoot.
ARSENAL'S LOSS
Arsenal were among Olise's admirers and the club was looking to bring him in before the Eagles swooped in.
Gunners fans are irked about missing out on valuable addition, when they had the chance in the summer.
After witnessing Olise's goal against Leicester City, which put the 19-year old on the map, Arsenal fans took it to Twitter to vent their frustration on the club's decisions.
One fan said: "I begged Arsenal to sign Michael Olise".
Another fan called Olise a 'baller'.
Whereas another rated Olise a 10 and Jude Bellingham a 8