The son of a local painter, Jean-Pierre-Tassaert was born in Antwerp and was briefly in London before settling in Paris, where he trained under the Flemish sculptor Michel-Ange Slodtz (1705-1764).
Few works from this period survive although he appears frequently in contemporary sale catalogues and regularly exhibited at the Salon. He seems to have been sought after for his mythological and amorous subjects as well as for his decorative sculpture.
In 1775 Tassaert was invited to Berlin by Friedrich II King of Prussia (1712-1786) for whom he executed various reductions of his own models and realised the decoration of the Berlin and Potsdam palaces. He remained in Berlin until his death.