His style combines the muscular anatomy of Michelangelo with the elongated grace of Parmigianino. In works like Naakte krijgers in gevecht and Twee klimmende mannen, Speckaert demonstrates a command of the human form in motion. He used bold, fluid lines to define musculature. He used dramatic foreshortening. This approach helped define the Romanist movement. Northern artists in this group adopted the scale of Italian Renaissance art. His compositions often feature twisting figures and athletic poses.

Modern collectors value Speckaert for the clarity and energy of his sketches. His drawings, such as Knielende figuur or the mythological Mars en Venus, offer a direct connection to the artist's process. These works function well in contemporary interiors. They balance classical subject matter with a gestural quality. The monochrome nature of his chalk and ink studies provides a clear aesthetic that complements various decor styles. His art is a bridge between the precision of the North and the drama of the Italian South.