The Israel Defense Forces (IDF) said they informed Rintalak's family of the news and expressed their "deep condolences".
They added that they will continue to push for the return of the body of Gvili, urging Hamas to "make the necessary efforts" to return him to his family.
Israeli officials are coordinating with the Thai embassy in Israel for Rintalak's remains to be returned to Thailand, the prime minister's office said in a statement.
Israeli and Thai authorities say both hostages were killed during the Hamas-led attack on southern Israel on 7 October 2023 and that their bodies were then taken to Gaza.
Under the first phase of the US-brokered ceasefire deal, which took effect on 10 October, Hamas agreed to return the 20 living Israeli hostages and the bodies of the 28 dead Israeli and foreign hostages still in Gaza within 72 hours.
All the living hostages were released on 13 October in exchange for 250 Palestinian prisoners and 1,718 detainees from Gaza.
So far, the remains of 23 dead Israeli hostages have been handed over, along with those of four foreign hostages - two of them Thai, one Nepalese and one Tanzanian.
In exchange, Israel has handed over the bodies of 345 Palestinians killed during the war.
Israel has accused Hamas of deliberately delaying the recovery of the hostages' bodies, while Hamas has insisted it is struggling to find them under rubble.
The slow progress has meant there has been no advance on the second phase of US President Donald Trump's Gaza peace plan. This includes plans for the governance of Gaza, the withdrawal of Israeli troops, the disarmament of Hamas and reconstruction.
The dead hostage still in Gaza was among the 251 people abducted by Hamas and its allies on 7 October 2023, when about 1,200 other people were killed.
Israel responded to the attack by launching a military campaign in Gaza, during which more than 70,100 people have been killed, according to the territory's Hamas-run health ministry.
