The Crieff-born star said he is using stress-busting techniques ahead of his debut in a production of the Tom Stoppard drama The Real Thing.
He has been using a £2.99 app called Conquering Anxiety, created by his friend Max Kirsten, a hypnotherapist and life coach.
The iPhone app includes hypnotherapy sessions, breathing exercises and lessons in thought field therapy (TFT).
It also encourages users to write down a series of phrases and read them aloud at the start of each day.
They include “Just for today I will not anger”, “Just for today I will not worry” and “Just for today I will show gratitude to all living things”.
The 43-year-old said the tool had been a huge help during warm-up shows this week.
He tweeted: “Going on Broadway for the first previews has been a nervy thing and my mate @Max_Kirsten’s app ‘Conquering Anxiety’ has been brilliant.”
He added: “My name in lights on Broadway. Big moment for a wee actor from Crieff.”
Speaking about the app, Mr Kirsten said: “This is a proven anxiety-busting program based on many years of successfully treating patients at my private clinic in London – not a generic hypnosis product.
“As a clinical hypnotherapist and success coach, I’ve seen a steady increase in the number of clients with anxiety problems in the current climate. I’m seeing more people who feel out of control and who are using self-destructive forms of behaviour to try to escape their negative feelings. Many have physical symptoms that confirm their stress. Insomnia, nausea, headaches and shallow breathing are common.”
McGregor has attended Mr Kirsten’s hypnotherapy sessions before to help him quit smoking.
The Star Wars and Trainspotting star has previously received critical acclaim for theatre roles in Guys and Dolls and Othello, as well as for his work in film and television.
He has previously told of his battle with stage fright when making his West End musical debut in Guys and Dolls nine years ago.
He said: “I do find it daunting going back to live theatre after movies. The rehearsals are the best part, it’s facing the audience that’s nerve-racking. It’s terrifying, but it’s so healthy for actors to be in theatre. It’s really good for us.
“The process is very difficult. On stage, you have to tell the whole story and I think it’s good for us to work together far more.
“I can’t wait. But I’ll really have to work to master the stage fright.”
McGregor stars alongside Hollywood actress Maggie Gyllenhaal in The Real Thing, about a couple who leave their partners to be together. It opens on 30 October at the American Airlines Theatre in Manhattan.