In a statement, the Ministry of the Interior and National Security said the three men were hanged after exhausting appeals, CNN reported.
The man convicted of "collaborating with Israel" was the third to be executed on that charge in less than a year. Two were hanged last summer.
The government of Gaza has been in Hamas's hands since 2007. The party won parliamentary elections in the Palestinian Authority in 2006 but the West Bank has been under control of the Fattah Party since Hamas seized power in Gaza.