His work belongs to the Hague School tradition. Vrolijk avoided the overly sentimental depictions of rural life common in the nineteenth century. Instead, he painted cattle and hay wagons with a quiet realism. In pieces like Hooiwagen in weiland or Twee koeien in een weiland, he used a muted palette of greens and greys. His brushwork is deliberate. He focused on the interaction between the animals and the damp Dutch light.

Modern collectors value Vrolijk for his ability to bring a sense of calm to a room. His watercolours and oils provide a window into a pre-industrial world without feeling dated. These prints suit minimalist or traditional interiors. The focus on nature and animals offers a grounded aesthetic. His depictions of the Scheveningen dunes or river scenes provide a connection to the Dutch countryside that remains relevant for contemporary decor.