Johnson picked up 126 of the 313 votes from Conservative party members of the lower House of Commons while former Brexit minister Dominic Raab was knocked out. Johnson had won the support of 114 of 313 Conservative Party lawmakers in the first round of the leadership contest.
Any candidate with 32 votes or fewer is eliminated. If all candidates have more than 32 votes, the one with the fewest is eliminated.
Foreign minister Jeremy Hunt picked up 46 votes, environment minister Michael Gove 41, international development minister Rory Stewart 37, and interior minister Sajid Javid exactly 33.
Johnson, the face of the official campaign to leave the European Union in the 2016 referendum, has promised to lead the United Kingdom out of the EU with or without a deal.
But parliament has indicated it will try to stop a no-deal Brexit, which investors warn could roil markets and shock the world economy, while the EU has said it will not renegotiate the Withdrawal Agreement that May agreed.
In his first broadcast interview since the campaign started, Johnson gave an unequivocal pledge that Brexit would happen by the latest Brexit deadline of October 31 and Britain had to prepare for a no-deal exit, which he said would not be a disaster.
"All those who say that we should delay ... I think they risk doing terminal damage to trust in politics. We have to get on and do this. We've got to be out by October 31," Johnson told BBC radio.
Further rounds of voting scheduled for Wednesday and Thursday will whittle the list of contenders down to just two.
The finalists will face the ruling party's 160,000 grassroots members in a vote next month to decide the winner.
(Inputs: Reuters, AFP)
Ex-foreign minister Boris Johnson picked up 126 of the 313 votes from Conservative party members of the lower House of Commons