Van Wittel was born into a Roman Catholic family. His father was a cart maker. Caspar studied painting in Amersfoort with the relatively obscure Thomas Jansz van Veenendaal for 4 or 5 years and then with the better known Matthias Withoos for 7 years.
His first extant works were made in Hoorn in 1672 to where he had fled after the French invasion and occupation of Amersfoort in the Rampjaar. He returned to Amersfoort where he was active until 1674, the year in which he left for Italy together with his friend Jacob van Staverden, another pupil of Withoos.