Isaac Herzog, the grandson of Ireland's first Chief Rabbi, was sworn in before parliament as the state's 11th president, replacing Reuvin Rivlin in the largely ceremonial post.
With his left hand on a Torah and his right raised, Herzog, a veteran of Israel's Labor party, said he was "humbled and thrilled" and vowed to be "everyone's president".
He bemoaned polarisation in Israeli society and the "unprecedented crisis" in its politics.
"My mission is to do everything to build up hope once again," said the 60-year-old, who is starting a seven-year term after beating out former headmistress Miriam Peretz in a vote among lawmakers last month.
Mr Herzog is son of Chaim Herzog, Israel's sixth president and a former ambassador to the United Nations, who grew up in Dublin.
The Israeli president exerts little power, with the prime minister wielding executive authority.
When Mr Herzog was elected, Benjamin Netanyahu was still premier, a post he had held for 12 years until he was dramatically ousted last month by his former chief of staff, now Prime Minister Naftali Bennett.
The presidency however assumed an outsized role during Israel's unprecedented spate of four elections in less than two years.
The president is charged with selecting the politician best placed to form a government, a closely-watched process after Israel's run of inconclusive votes.
The president does have the power to grant pardons -- a potentially important function as Mr Netanyahu stands trial for alleged fraud, bribery and breach of trust, charges he denies.
The scion of one of Israel's most prestigious families, Mr Herzog was first elected to parliament in 2003, but was most recently leading the Jewish Agency for Israel, an organisation focused on relations with Jewish immigrants and the diaspora.
He is also nephew of the famed diplomat and statesman Abba Eban.
The new president supports the two-state solution to the conflict with Palestinians.
During his 2015 campaign he vowed to relaunch a peace process, even saying he was prepared to "remove" Israeli settlements if necessary.