The 40-year-old Chamisa said Zimbabweans were craving generational change in the landmark July 30 elections. The vote will pitch him against President Emmerson Mnangagwa, a septuagenarian who was once a pillar of the Mugabe regime.
"People are connecting with young leadership," Chamisa declared.
"The world is moving... young people are taking charge, look at France, look at Canada, look at New Zealand - look at the United States," he said.
Barack Obama became US president aged 47, Justin Trudeau became Canadian prime minister at 43 while France's Emmanuel Macron became president at just 39.
"Most of the young people out there are connecting with our message, are connecting with my age - they are connecting with the vision I'm articulating," said Chamisa.
Chamisa has led the Movement for Democratic Change (MDC) since the death of his mentor and predecessor Morgan Tsvangirai in February.
He will face off against 75-year-old Mnangagwa, whose Zanu-PF party - which has ruled Zimbabwe since independence 38 years ago - has sought to portray Chamisa as a political novice.
"I'm happy that they are accusing me of being young, it's an offence that I take," said Chamisa from behind an Apple laptop in his office overlooking Harare's Africa Unity Square.
The public space was once a site of major protest against former president Robert Mugabe, 94, who ruled for 37 years in which he clamped down hard on his political opponents.
"Change is in the air - it's almost everywhere," Chamisa said, suggesting that Mugabe's exit from public life was "the beginning of that change".
Mugabe resigned in November after an unprecedented military challenge to his rule that saw armoured personnel carriers on the streets of Harare and drew accusations from some observers that Zimbabwe had suffered a coup.
