Former England under-21 international Willock joined the Magpies on loan from the Gunners in January 2021 before signing permanently that August.
The box-to-box midfielder began his career with Arsenal, where he featured for their youth teams alongside his brothers Chris and Matty.
After making his senior bow in a League Cup clash with Doncaster Rovers in September 2017, his Premier League debut came at St. James' Park against United in April 2018. He featured in the Europa League for Arsenal, going on to make a total of 78 appearances for them, netting 11 times in the process before his loan move to Tyneside midway through the 2020/21 season.
Willock's temporary spell with the Magpies was a huge success, with the energetic youngster netting seven times in his final seven games, becoming the first United player to achieve such a feat since Alan Shearer.
And Newcastle made the move permanent ahead of the start of the 2021/22 campaign, with Willock penning a six-year deal at St. James' Park and establishing himself as a driving force in the United midfield.