Van Rooijen was born in Utrecht, but moved to Houten with his parents at a young age.[2] In 2008, he moved from local amateur club Delta Sports '95 to the youth academy of FC Utrecht. He signed his first youth contract with that club in 2015,[3] before being promoted to the second team competing in the second-tier Eerste Divisie the following year, in 2016. On 5 August 2016 he made his professional debut for the team, starting on the opening day of the 2016–17 Eerste Divisie in a 4–1 away loss to NAC Breda at the Rat Verlegh Stadion.[4] On 22 December 2016, his 18th birthday, he signed a contract extension with FC Utrecht until 2020, with an option for an additional year.[5]
In March 2020, the option was exercised by FC Utrecht, automatically extending the deal until 2021,[8] and a few months later, in July 2020, he signed a new contract keeping him part of Utrecht until 2023.[9] Earlier that year, on 17 January 2020, Van Rooijen, who had become team captain of Jong Utrecht, had made his debut for the first team in the Eredivisie in a 3–3 away draw against PEC Zwolle.[10] Due to a number of injuries in the first team, head coach John van den Brom included Van Rooijen in the starting lineup that day, before replacing him in the 66th minute for Urby Emanuelson after suffering a groin injury.[11]
Van Rooijen was sent on a season-long loan to Eerste Divisie club Excelsior on 4 August 2020.[12] He would play regularly for the club, making 26 total appearances in which he scored once.[1] After the season, he returned to Utrecht.[2]
VVV-Venlo
Van Rooijen moved to VVV-Venlo on 26 July 2021, signing a two-year contract with an option for an extra season.[13][2] He made his debut on the first matchday of the 2021–22 season, starting in a 2–2 home draw against NAC Breda.[14] On 5 November 2021, he scored his first goal for the club, equalizing in the home match against Jong Ajax, which would eventually finish in a 3–1 loss.[15] He made 26 total appearances in his first season with VVV, scoring six goals.[1]
Van Rooijen left VVV at the end of the 2022–23 season, as his contract was not extended.[16]
Manchego Ciudad Real
On 25 August 2023, Van Rooijen signed with Spanish fourth-tier Segunda Federación club Manchego Ciudad Real.[17] He made his debut for the club on 3 September, coming on as a substitute in the 59th minute as Manchego lost 1–0 to Águilas.[18] He was a regular starter throughout the season, during which Manchego suffered relegation to the Tercera Federación.[1][19]
TOP Oss
On 28 June 2024, Van Rooijen returned to the Netherlands, signing for Eerste Divisie club TOP Oss on a two-year deal.[20][21]
^"OFICIAL FICHAJE – MITCHELL VAN ROOIJEN" [OFFICIAL ANNOUNCEMENT – MITCHELL VAN ROOIJEN] (in Spanish). Manchego Ciudad Real. 25 August 2023. Retrieved 25 August 2023.