The 27-year-old Israeli international joins from Ashdod for an undisclosed fee, after spending last season on loan at Easter Road.
"It was not so easy, but I'm happy to get it done finally," Marciano told Hibs TV.
"My first season was hard and I didn't really know what Hibs means, but it was an amazing experience."
Marciano made 28 appearances for Hibs last season as the Edinburgh club secured their return to the top-flight by winning the Championship.
He is the club's fourth signing of the summer - after Efe Ambrose, Danny Swanson and Simon Murray - and will compete with Ross Laidlaw for the starting goalkeeper slot in the Premiership this season.
"I wanted to become a better player when I came here and I think I did that," Marciano said.
"That's why I wanted to come back to Hibs - because I have everything here to be a better player.
"And of course the fans are amazing and it's a privilege to play in front of them every week."

A Church commission inspected the bust in Crimea after Natalya Poklonskaya made the claim on a Russian TV channel.
Revolutionaries murdered Nicholas II - the last tsar - with his wife and children in 1918. The Church made most of the murdered family saints in 2000.
President Vladimir Putin has done much to restore the Church's prestige.
In the past some Russian Orthodox worshippers have claimed to see myrrh seeping from holy icons - but not from any busts of the old ruling family, the Romanovs.
Ms Poklonskaya's claim about the bust in Crimea's capital Simferopol was derided by some on Russian social media.
She claimed it was a sign that the dead tsar wanted Russia to "prosper and be great again", 100 years after his abdication.
The Crimean branch of the Russian Orthodox Church said its commission "did not detect traces of holy secretion on the bronze bust... nor on icons in the [nearby] chapel".
The Church said the chapel's priest "should continue observations, and if there are any traces of holy secretion he should immediately inform the bishop and the commission".
In the past some Roman Catholic worshippers have also made claims about weeping statues of the Virgin Mary.
Ms Poklonskaya was born in Ukraine and has lived in Crimea since 1990. She was appointed Crimean chief prosecutor in May 2014, after Russian forces had annexed the peninsula from Ukraine.
She has been a deputy in the Duma - Russia's lower house of parliament - since September 2016.
Hibernian have completed the permanent signing of goalkeeper Ofir Marciano on a four-year contract.
[NEXT_CONCEPT]
The Russian Orthodox Church says it has not found any fragrant myrrh seeping from a bronze bust of Tsar Nicholas II, after a Russian MP made such a claim.