The actor took to Twitter to voice his fury after the Brexit Party leader was told off by Irish MEP Mairead McGuinness for waving a union flag and using the word "hate".
Scottish Heughan tweeted: "Disgusting, childish imbeciles... I cannot believe we are being led out of Europe by this bunch of flag waving buffoons. Sickening."
His comment received almost 6,000 likes on the social media site with
Norah Zeroka sympathised: "Oh Sam. You now have an inkling of how some of us in the US have been feeling these last three years. It just never seems to end. My sincere condolences."
Lucy Sharvet agreed, writing: "They are idiots and they think that business will go on just as usual. Scotland needs to be independent or it will get dragged into a huge financial mess."
Nancy Staack added: "Believe me, we feel for you. Fighting for our lives and democracy here."