Menno Geelen studied Business Administration at Radboud University and completed Leadership and Negotiation Programmes at INSEAD Business School. He joined Ajax in 2010 and became Commercial Director in 2016. Under his leadership, Ajax experienced significant commercial growth, which provided a sound financial basis for further investment in football.

In May 2024, Menno was appointed interim CEO of AFC Ajax and on 1 July 2025 he officially became the club's CEO.

Since Menno joined Ajax, the club has won seven domestic league titles and two domestic cups. In that period Ajax also played in the UEFA Champions League group stage 10 times, including five consecutive seasons between 2018/19 and 2022/23. The highlight was the 2018/19 season; starting in the second qualifying round, Ajax eliminated defending champions Real Madrid and Juventus and reached the semi-finals. Ajax has won the Champions League four times (1971, 1972, 1973, 1995), the UEFA Cup Winners' Cup (1987), UEFA Cup (1992) and the Intercontinental Cup (1972, 1995).

Menno is also chairman of the board of the Ajax Foundation and a member of the UEFA Club Competitions Committee.