Three other defendants were sentenced to life and 22 others were sentenced to 15 years in prison. Three of the defendants were acquitted.
The defendants were accused of killing the policemen in an ambush in Sinai in August 2013, one month after the ouster of Islamist president Mohamed Morsi.
They were also convicted of espionage with Al-Qeada militant group among other charges.
The sentence was first pronounced in October, but was not final until it is approved by the Grand Mufti, who according to Egyptian law must review all death punishment verdicts.
Militant attacks against police and army have increased since the ouster of Morsi last Year.
Over 500 security personnel have been reported killed since then.