He spent some four years in Italy and was one of the founders of the Bentvueghels circle of northern painters in Rome.

In 1621 he was, along with Cornelis van Poelenburch and Willem Molijn, a founding member of the circle of Dutch and Flemish artists in Rome known as the Bentvueghels.

The Caravaggesque style of van Bijlert's early paintings shows itself in the use of strong chiaroscuro, the cutting off of the picture plane to create a close-up image and the realism of the representation.

In the 1630s he also painted compositions with small figures, usually representing genre scenes of brothels or musical gatherings.

Van Bijlert also painted the portraits of eminent citizens of Utrecht such as burgomasters and nobles.