Alex Younger, head of the Secret Intelligence Service as MI6 is officially known, told the Guardian newspaper he wanted the agency to reach communities who were "selecting themselves out".
"We have to go out and ask these people to join us," said Younger, who rarely makes public comments, in the interview published on Thursday.
"That was the only way of recruiting people, a tap on the shoulder. That was the way I was recruited," he said.
"We have to go to people that would not have thought of being recruited to MI6. We have to make a conscious effort. We need to reflect the society we live in."
In 2015, Britain announced it would recruit another 1,900 spies to deal with the threat posed by Islamist militants.
The Guardian said MI6 would launch a recruitment campaign next week in a drive to take its numbers to 3,500, the largest in its history.
MI6, however, said it battled with the enduring image that its officers were all like its greatest fictional agent James Bond, currently portrayed by actor Daniel Craig.
"There is a perception out there that we want Daniel Craig, or Daniel Craig on steroids. He would not get into MI6," said the agency's female head of recruitment, who like all its agents apart from Younger is anonymous.
"We need to get that message across because it is so embedded, and we have to get around that. They may well be able to use a revolver. But that is not really what we are looking for."
The Guardian said Younger would not be drawn on specific dangers Britain faced, but had warned the agency needed to be "upstream of the threats".
"The terrorist threat has grown but that has not resulted in a diminution of threats posed by hostile states," he said. "They have ways of posing a threat to us that they did not have before."