Being part of "Brand Britain" is a major benefit to Scotland's tourism industry which is threatened by independence, Alistair Darling said.
The success of the sector is down to Scotland's own "unique identity" but also sharing the international profile of the UK, according to the leader of the Better Together campaign.
Mr Darling made the comments as he took a cruise on Loch Lomond to mark the launch of Tourism Together, a group of people working in Scotland's tourism industry who back a No vote in September's referendum.
The former chancellor said: "Brand Scotland is known throughout the world. It gives us our own unique identity.
"But we also benefit from being part of something bigger. Brand Britain benefits us here in Scotland just as much as it does the people living elsewhere on our isles.
"The global recognition and international profile of the UK attracts people to the great tourist attractions of Scotland - from our cities like Glasgow and Edinburgh to idyllic spots like Loch Lomond and Cairngorms.
"It's that combination, that best of both worlds, that makes Scotland's tourism industry the success it is."
Mr Darling set sail from Balloch, West Dunbartonshire - the gateway to the Loch Lomond and the Trossachs National Park and a major tourist hotspot.
He took an hour-long cruise on the Silver Dolphin, speaking to members of Tourism Together about why they are supporting a No vote.
The Edinburgh MP said it is "full steam ahead" for the Better Together campaign, despite it being described by the Yes camp as a "sinking ship".
He said: "Visitors come from the rest of the UK because there's no difficulty in coming here - they've got the same currency, no border controls.
"We also attract a lot of visitors who come to the UK and then to Scotland, and our overseas embassies and consulates are a massive help to this industry.
"If you speak to anyone in the tourist industry they say, look, we need the strength of the UK to help us do even better in Scotland.
"Most of the people on board are involved in the tourist industry and they make the point that if you make people think twice about coming, you can lose people.
"A lot of them have family businesses built up over many, many years and the advantage they've got, in terms of marketing, in terms of simply getting people here, of being part of one country without any difficulties - that just makes them say, look, we're far better if we stay together rather than have all the risks, the uncertainty - particularly over Europe and so on - that would make a real difficulty and a real problem for people coming to visit Scotland."
Also on board the boat was Murdo MacLeod, whose family runs a small hotel business on Loch Long.
He said: "There's a lot of people locally who have never really been active in politics in any way whatsoever but have just become increasingly concerned about the possibilities of independence and the consequences of it.
"For the first time, really, in my memory we've got ordinary people who are entering the fray to try to influence the outcome.
"Put simply, a lot of us don't see independence as a positive outcome of this debate. I think there's a number of reasons why it (independence) might have an adverse impact. There are currency concerns. The EU issue is important as well.
"Most of us have been on holiday in the European Union and elsewhere and we all use credit cards. We reckon it's going to put about 7% on the average credit card bill, if Scotland is not part of the UK, to go to England, Wales, Ulster."
He added: "I am as Scottish as they come but my children are only half Scottish and my grandchildren only a quarter Scottish, and it goes on and on and on. Unpicking this web that's been built over the years by our founding fathers is not going to be something that's either possible or desirable."
Mr Darling said the offer of further devolution for Scotland from all three of the main unionist parties has boosted momentum for No in the independence campaign.
He said: "As we look ahead to next week's Commonwealth Games, our No Thanks campaign has all the momentum and it's the Nationalists' campaign that has all the problems.
"They wanted to suggest that a No vote was a vote for no change. Now all three main political parties are promising significant extra powers for Scotland backed by the strength, stability and security of the United Kingdom.
"We are offering what most people in Scotland want. The result is that all across our nation, more and more of us are saying no thanks."
Yes Scotland chief executive Blair Jenkins said: "A poll earlier this month put Yes at 47%, within touching distance of a win in September, and another poll at the weekend showed that fewer than four in 10 people believe the No campaign's vague and confused offer of more powers if there is a No vote. The same poll also showed that a Yes vote increases when Scots are asked to consider the UK Government's proposed in/out referendum that could drag us out of the EU against our wishes.
"Scotland has a very powerful and flourishing tourism industry, worth £10 billion, that we can expect to grow even more with the strengthening of Brand Scotland - and with the interest generated from tourists wanting to visit the world's newest, and one of the most welcoming, countries.
"The No campaign's bogus claims about tourism have already been disproved. In a poll earlier this year by a tourism consultancy, 85% said that independence would make no difference to Scottish tourism, and 43% of those who thought it would make a difference said independence would make them want to visit Scotland 'even more'."