Hofer took over the Freedom Party (FPOe)'s leadership in May after Heinz-Christian Strache resigned, both as party head and Austrian vice-chancellor, in the wake of the "Ibiza-gate" corruption scandal.
That scandal brought down the government, a coalition formed in late 2017 between the FPOe and the People's Party (OeVP) of then chancellor Sebastian Kurz, with fresh elections set for September 29.
On Saturday, FPOe delegates formally elected Hofer, Strache's former deputy, to head the party.
"It is our goal to become Austria's strongest party - because we are able to do so and because Austria needs us," Hofer told the party convention in the city of Graz in southeastern Austria.
Despite the scandal, the FPOe stands at around 20 percent in voter polls, neck-to-neck with the Social Democrats (SPOe).
The OeVP remains the strongest party but unlikely to be able to form a majority government by itself, according to polls.
Hofer said his party would continue to fight "political Islam" and would also take on new themes, such as protecting the environment.
"I will take the necessary steps to bring this party forward," the former transport minister said.
Analysts say Hofer -- a 2016 presidential candidate who surprised many by his strong performance -- faces a battle to unite party hardliners and overcome the Ibiza-gate scandal.
Hidden video footage filmed in the resort island of Ibiza in 2017 and released in May by German media showed then FPOe leader Strache appearing to offer contracts to a fake Russian backer in return for campaign help.
Hofer admitted the scandal had made for a "really difficult phase" for the FPOe, but despite this solicited a round of loud applause for Strache for his commitment.
Strache, who led the party for 14 years, did not attend the convention.
Those who did attend said the FPOe stood united.
"Everyone thought they can destroy the FPOe. (Instead) it is becoming a bigger and bigger family," Robert Spoerk, 60, an FPOe member who runs a coffee shop in Graz, told AFP.
Two weeks ahead of national polls, Norbert Hofer vowed to fight "political Islam" and also take on new themes, including protecting the environment, after delegates formally elected him leader of Austria's far-right Freedom Party.