The Irish singer was amongst 300 of his countrymen and women invited to an event celebrating the contribution of Irish people to Britain.
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Niall joked he would invite the Queen to a show after meeting her for the second time
He said: "It's an absolute honour to be here with two great countries coming together - I couldn't believe it when I got the invitation. To have met Her Majesty again was a great experience."
"[The others] were really happy when I told them. They know it's an Irish thing so they're not being left out. I might ask her if she wants to come to a show."
Niall and his four bandmates – Harry Styles, Liam Payne, Louis Tomlinson and Zayn Malik – met the Queen after their Royal Variety Performance in November 2012.
X Factor judge Louis Walsh was also at Buckingham Palace during an evening celebrating the contribution of Irish people to Britain.
On this royal visit, Niall instead rubbed shoulders with famous Irish faces from the worlds of sport, art, business, politics and community service.
Amonth them were former X Factor judge Louis Walsh and fashion designer Orla Kiely.
A Buckingham Palace spokesperson said of the evening – which was set up ahead of next month's history-making official state visit from Irish President Michael D Higgins: "It was a really fun evening - great company and extremely relaxed.
"Her Majesty seemed to enjoy the craic."