van Dijk (born 22 November 1971) is a Dutch non-executive director and a politician of the Reformed Political Party (SGP).

While a member of the body in 2024, a motion of Van Dijk was carried calling on the Dutch Health Council to investigate the appropriateness of the policy regarding gender-affirming care for transgender minors.

Minister Conny Helder had advised against the motion, saying that periodic evaluations were already occurring, while Van Dijk raised concerns about safety and effectivity.

Nowadays he is among others a member of the supervisory board of the Reformed news media company Erdee Media Groep as well as of the care facilities Sorg and Lelie Zorggroep, and an elder in the Restored Reformed Church at Waddinxveen.

Diederik van Dijk is married with five children, and he lives in Benthuizen.