He made the remarks in an interview with The Canadian Press on Thursday prior to his upcoming official state visits to Chile and Colombia in the coming week.
Canadian mining companies are active in both countries, and the extractives industry is frequently a lightning rod for broad criticism that it can run roughshod over local, often indigenous populations.
Overall, Johnston said Canadian companies are leaders in corporate social responsibility, but there's always room for improvement.
He said when some companies periodically fail to meet the standards of proper corporate behaviour, they are hurting the economic chances of those that are doing good work.
"In the mining area, one could argue that Canada sets the standard for the world in terms of what investment practices should be," Johnston said in a wide-ranging discussion at his official residence, Rideau Hall.
"And that where Canadian companies fall short I think that certainly the Canadian government is pretty alive to the fact that — live up to your promises because if you don't it's going to be bad for all," he added.
"And that where we fall short to say: this is not the Canada brand that we want to see."
Johnston said he has developed a deep interest in the mining industry, having grown up in northern Ontario.
He is undertaking his latest trip to help Canada's economic and trade ambitions in the Americas, which have been a priority of the Harper government, but have faced some sputtering.
The government is also a heavy promoter of Canadian miners. Last week, two cabinet ministers — Trade Minister Ed Fast and Natural Resources Minister Greg Rickford — gave speeches about the need to protect the "brand" of an industry that is comprised of 1,200 Canadian companies, operating 8,000 properties in more than 100 countries, accounting for 35 per cent of the world's exploration spending.
But the ministers signalled that Ottawa could withdraw financial and political support from Canadian companies that don't measure up on the social responsibility scale.
Johnston said Canada leads the world in corporate social responsibility.
"That said, it's a journey in progress, and we still have a ways to go," Johnston said.
"We have a lot at stake economically, but we also have a lot at stake as a country that prides itself on operating with integrity and sustainability in its operations both here and abroad."
Johnston's trip to Colombia will have a profound personal tinge: he'll be accompanied by two of his granddaughters, both Colombian-born and adopted by his oldest daughter, Debbie.
They'll be paying their own way, Johnston said.
"They are a constant source of joy," he said.
"When those two come to Rideau Hall they are kind of gymnastic, so they do cartwheels up and down the corridor out there."
Johnston also welcomed the government's decision this past week to lift a travel visa on Chilean travellers, saying it would open up business opportunities.