Netanyahu's rival Gideon Sa'ar, a former Education Minister, garnered only 28 per cent of the ballots cast on Thursday, reports Xinhua news agency.
The result will enable Netanyahu to lead Likud into the national elections on March 2, 2020 and also gives him another opportunity to form a coalition government after failing in two previous attempts this year.
"Great victory!" Netanyahu wrote on Twitter earlier after an exit poll put him on course for about 70 per cent of the vote.
"With the help of God and with your help, I will lead the Likud for a great victory in the elections and will continue to lead Israel to great achievements," he added.
In a tweet, Sa'ar congratulated Netanyahu and said he would support him in the national elections.
"I am absolutely comfortable with my decision to run," he said. "Whoever isn't ready to take a risk for the path he believes in will never win."
Likud members cast their ballots on Thursday to choose their leader for the next national elections.
Earlier in December, Sa'ar, 53, announced that he would run against Netanyahu, 70.
The embattled leader is facing criminal indictments in three separate corruption scandals, in which he is charged with bribery, fraud, and breach of trust.
He denied any wrongdoing and said the charges are part of "a witch hunt".
Netanyahu failed to form coalition governments after the last two national elections.
The upcoming national elections will be the unprecedented third time Israelis would cast their ballots in less than a year, amid political deadlock that has paralyzed the Israeli political system over the past months.
( With inputs from IANS )