His style belongs to the late French Baroque, defined by a preference for dramatic compositions and clear narrative structures. In works like 'Saint Paul with Saints', he used strong contrasts to direct the eye across the canvas. Unlike the later Rococo artists who favoured pastel tones, Robert maintained a more traditional palette. His training as an engraver influenced his painting style, resulting in a firm sense of structure and form that remained consistent throughout his career.

Collectors today value Robert for his ability to convey a sense of gravitas without the heaviness of earlier seventeenth-century art. His prints and paintings offer a window into the formal aesthetics of the Regency period in France. These works provide a sophisticated atmosphere for modern rooms, especially those with high ceilings or traditional architectural details. The clarity of his compositions makes his work a popular choice for those seeking a sense of historical continuity in their home decor.