Pamela Nash, who was the MP for Airdrie and Shotts until 2015, replaces Graeme Pearson as chief executive of the organisation. Mr Pearson will continue as a director.
Ms Nash, 33, will take charge of an organisation which has grown to around 25,000 supporters since being founded in 2015.
“Like so many other people all over Scotland, I campaigned in the 2014 referendum to keep us part of the UK because I believed it was best for our country. I am proud of my No vote and hoped we could move on together after such a decisive result. Sadly, many nationalists are refusing to take no for an answer," she said.
“That’s why I want to keep making the positive case for Scotland’s place in the UK and protect the economic and social benefits we get from this partnership. I believe there is a real need for a campaign like Scotland in Union to counter the divisive rhetoric of nationalism and remind people why we are better off in the UK.”
Nash was the youngest MP returned in the 2010 election when she took office at the age of 25.
Alastair Cameron, founder and Executive Director of Scotland in Union, said: “Pamela’s experience in campaigning will be real asset to Scotland in Union and she will be a strong advocate for the majority of Scots who want to stay in the UK. Her appointment marks a new phase in our campaign as we look to move past the unwanted threats of a second referendum and help create a Scotland which prospers and thrives in the UK.
“I would like to thank Graeme Pearson for leading our campaign so successfully for the last nine months during a momentous time in Scottish politics. We are delighted we will continue to benefit from his counsel and support as a director.”