From Ramallah to Beirut, Amman, Damascus, Baghdad and Cairo, people have distributed sweets, danced and chanted prayers in support of resistance to Israel's long-standing occupation of Palestinian territories.
"My entire life, I have seen Israel kill us, confiscate our lands and arrest our children," said Farah al-Saadi, a 52-year-old coffee vendor from Ramallah in the Israeli-occupied West Bank.
"I was pleased by what Hamas did," said the man, whose son is in Israeli detention, adding however that he feared the scale of Israeli retaliation.
On Tuesday, dozens of people took to the streets of Ramallah, home to the Palestinian Authority of President Mahmud Abbas, to rally in support of Hamas, and AFP correspondent said.
Late Tuesday, more than 4,000 people rallied in central Amman shouting "Go, go Hamas" and "From Gaza came the voice, revolution, revolution until death."
Hours after the shock operation began on Saturday, Palestinian supporters distributed sweets in south Lebanon and the capital Beirut.
Israel and Lebanon are still technically at war.
Residents of the southern port city of Sidon set off firecrackers and gathered in public squares as mosques blasted chants praising "Palestinian resistance fighters who are writing the most wonderful, heroic epic".
A rally was held at the American University of Beirut, where 18-year-old Palestinian student Reem Sobh said: "We are unable to carry weapons but at least, we are able to support them."
Social media has been flooded with expressions of support for Hamas including the hashtag in Arabic #Palestine-is-my-cause among the most widely trending on X, formerly Twitter.
On Instagram, Lebanese comedian Shaden Fakih explained why there was such a wave of support.
"What do you expect from Palestinians? To get killed every day and not do anything about it... to die silently?" she said in a video.
"They will carry arms and fight back. This is their right," she added, noting that she "can be against Hamas and still support any armed resistance against the oppressor, against (Israeli) apartheid".
In the Tunisian capital, schools raised Palestinian flags and a coalition of organizations and political parties have called for massive solidarity rallies.
The presidency declared its "full and unconditional support of the Palestinian people" and of their right to resist occupation.
Nothing to lose
In Damascus, the Palestinian flag lit up the city's opera house.
Syrian university employee Marah Suleiman, 42, said the Hamas attack "stirred up a feeling within us that had not been moved for many years, and revived the spirit of resistance".
Palestinians "have nothing to lose after all the killing, destruction and displacement they have been subjected to," she said.
In Egypt, football fans turned matches into displays of solidarity, with pro-Palestinian chants.
In the war-scarred Iraqi capital Baghdad, Iran-backed paramilitaries trampled and torched Israeli flags during rallies in Tahrir Square.
Even Arab Gulf states joined the wave of solidarity despite the US-brokered Abraham Accords, which saw Israel normalize relations with the United Arab Emirates and Bahrain in 2020.
The two countries released statements relatively sympathetic to Israel and condemning the deaths of Israeli civilians, but the popular mood told a different story.
Expressions of solidarity with Palestinians also filled social media in the UAE, and prominent Emirati analyst Abdulkhaleq Abdulla condemned Israel's attacks on Gaza as a "campaign of genocide" on X.