Those without web access risk getting left behind, warned Ms Lane-Fox
The poorest six million Britons who are not online will be the main focus for the UK's digital champion.
In her first public speech since being appointed, Martha Lane Fox spoke about her priorities.
Although 17 million Britons do not have net access, Ms Lane Fox said she wanted to concentrate on the six million "at the bottom of the pile".
Familiarity with the web would help these people learn, save money and compete better for jobs, she said.
Speaking at the Reboot Britain conference in London, Ms Lane Fox said she considered herself "lucky" to be asked by the government to be digital champion and given the job of getting people online.
In her first two weeks in the job, Ms Lane Fox said she had been visiting some of the government's UK Online Centres to meet people who were only now just getting to grips with the web.
Those on the wrong side of the digital divide were disadvantaged in many ways, said Ms Lane Fox. Studies showed, she said, that those familiar with the web earned more, performed better in job interviews, could save money by shopping online and had an easy route to keeping their skills fresh.
Among those 17 million Britons not online was a group of six million who were "the most socially and economically disadvantaged people we have in this country", she said.
"We are really going to focus, I hope, on the six million that are at the bottom of the pile. Partly because that's the right thing to do and partly because we know quite a lot about these people - who they are and where they live.
"I am sure we can put our arms around the problem," she said.
"It should matter to all of us because 80% of government interactions are with the bottom 25% of society," said Ms Lane Fox. "By keeping that 25% offline you are inherently keeping the cost of government high."
Ms Lane-Fox said inspiring people with technology should help to motivate them to take it up and get more out of it.
"It's the incredible human stories that show how it can be transformational in people's lives," said Ms Lane Fox.