Konstantinos was a first cousin of Evangelos Zappas.
About 1835, he immigrated and settled in Bucharest at his cousin's invitation to become his assistant.
After Evangelos Zappas' death in 1865, Konstantinos inherited the income from the properties and was at the same time the executor of his cousin's will.
Konstantinos was instrumental in the construction of the "Exhibition Space" the Zappion Exhibition Hall known as Zappion today. The construction began in 1874, under the supervision of the French Architect Francois Louis Florimont Boulanger (1807-1875), and was completed, after Boulanger's death, in 1888, by the Danish Architect Theofilus von Hansen (1813-1891).
Konstantinos was himself a great benefactor. In 1875, he build the Zappion Girls school in Istanbul. At the same time he financed the construction of schools in numerous Greek villages, including Lampovo.
In his will, he left everything he owned to Greece.