The 1D singer was flying solo without his bandmates at the reception, which was held by Her Majesty to celebrate Ireland’s vibrant culture.
Niall didn’t seem too nervous about making his trip to the royal residence and even joked that the Queen could be a Directioner.
“'I might ask her if she wants to come to a show,” he should shortly before being introduced to her.
Super sweet Niall even tweeted a special thank you to Buckingham Palace after the event, sending a photo and writing: “I would to thank @BritishMonarchy and of course queen Elizabeth for her invite to Buckingham palace yesterday evening”.
The Official British Monarchy account has even replied though we doubt the response is from the Queen herself.
“Thanks for the photo - glad you enjoyed the reception!” the reply reads.
This isn’t the first time the Irish singer has met the Queen, though last time - at the Royal Variety Performance in 2012 - he had his bandmates there for support.
Niall has had a pretty hectic schedule this week and he reportedly made his appearance at the palace after a busy morning rehearsing with his bandmates.
Earlier this week, the lads were seen filming a new music video in Somerset where temperatures close to zero left them clutching hot water bottles and bundling themselves in blankets.