Like so much of Scottish culture, the person most frequently credited/blamed for inventing the whole notion of Bonnie Scotland is Sir Walter Scott, author of Rob Roy. Scott was the first English-language author to have a truly international career in his lifetime, with many contemporary readers in Europe, Australia, and North America.
Bonnie Scotland is also the name of a 1935 American film starring Stan Laurel and Oliver Hardy, produced by Hal Roach and directed by James W. Horne. Although the film begins in Scotland, a large part of the action is actually set in British India.
You can find out more about Sir Walter Scott and his legacy to the Scots people in Scottish Miscellany: Everything You Always Wanted to Know About Scotland the Brave.