The court said in a brief statement that a 23-year-old man from the Zeitoun area south of Gaza City had been sentenced to death on espionage charges. It did not provide his name.
Three other men who "fled from justice" were also found guilty in absentia, it said.
A court source told AFP the four were convicted on "charges of spying for the occupation", including "surveillance" and providing information about cars and homes to help Israel plan alleged assassinations.
Hamas took over the Gaza Strip in 2007 after a battle with Fatah, which runs the Palestinian Authority. Eighty of the death sentences have been given in Gaza since that date.
Islamists Hamas have previously carried out executions against those accused of dealing with Israelis, with the killings sometimes taking place in public squares.
Under Palestinian law, collaborators, murderers and drug traffickers can face the death penalty.