The pair were said to have fallen out during the band's hiatus and Coyle admitted last year that she saw the rest of the group as colleagues and not friends.
Cole reportedly texted Coyle after her guest appearance at the Capital FM Summertime Ball on Saturday and arranged a meet-up at London's Rose Club.
"Cheryl thought it would be the perfect chance to get Nadine out," a supposed insider told Metro.
"They do actually get on and speak. Their diaries have just been out of sync over the years."
They added: "The girls had an amazing night catching up. All of Cheryl's hot American dancers were out as it was partly her send-off for them before they head back to the States."
Production team Xenomania confirmed last month that Girls Aloud are recording new material.
They noted that Kimberley Walsh, Nicola Roberts and Sarah Harding had already been in the studio and that Coyle would follow soon.
Photo gallery: Capital Summertime Ball in pictures: