The pair have been rumoured to be dating for some time, but the X Factor judge has always refused to confirm whether the reports are true.
However, the pair have been pictured in the Sunday Mirror holding hands and frolicking in the sea during a break at the Coco Palm Resort in the Maldives.
"What I will say is I'm really happy and have the best boyfriend - he's very supportive in what I'm doing with the show," Contostavlos said recently. "He's my rock - he's been there for me throughout the past few months. I couldn't be doing what I'm doing without him."
Contostavlos, who guided Little Mix to victory on the latest series of The X Factor, will fly to Los Angeles within the next few weeks to record new material and is hoping to release her debut solo single in April.
She has previously warned other women to stay away from her boyfriend in a post on Twitter.