In 2023, Dennekamp released a documentary focusing on the impact of climate change in the Netherlands. The documentary explored the effects on agriculture, urban planning, and coastal defenses, offering a comprehensive look at how the country is adapting to environmental challenges.

Gert-Jan Dennekamp was awarded the prestigious De Tegel award in 2020 for his outstanding investigative journalism. His work on exposing corruption and financial misconduct was recognized for its depth, accuracy, and impact on public policy and awareness.

In 2018, Dennekamp led an investigative report on tax evasion practices in the Netherlands. The report uncovered several loopholes exploited by corporations, sparking a national debate on tax policies and leading to discussions in the Dutch parliament about potential reforms.

During the European migrant crisis in 2015, Dennekamp reported extensively on the situation, traveling to various hotspots in Europe to document the challenges faced by refugees. His reports highlighted the humanitarian aspects of the crisis and the political responses across different European nations.

In 2010, Gert-Jan Dennekamp joined Nieuwsuur, a prominent current affairs program in the Netherlands. At Nieuwsuur, he continued his focus on investigative journalism, contributing to the program's reputation for in-depth analysis and comprehensive reporting on both domestic and international issues.

After his stint as a foreign correspondent, Dennekamp returned to the Netherlands and resumed his role at NOS as a senior reporter. He was tasked with covering major national and international stories, leveraging his experience from the Middle East to provide nuanced perspectives.

In 2000, Dennekamp was posted as a foreign correspondent in the Middle East, where he covered significant events such as the Israeli-Palestinian conflict. His reports provided Dutch audiences with critical insights into the complex political and social dynamics of the region.

Gert-Jan Dennekamp began his career at NOS Journaal in 1995, where he honed his skills in broadcast journalism. During his tenure, he was involved in producing and reporting on a wide range of news topics, gaining valuable experience in the fast-paced environment of a major newsroom.