Wendy Fawell, 50, of Otley, had been at the Ariana Grande concert at Manchester Arena with her 15-year-old daughter Charlotte and friends.
Ms Fawell was reported to have been about to leave the concert with Charlotte, along with a friend and her sons, when they were caught in the attack.
Charlotte was taken to hospital in Oldham and her brother, Adam Fawell, 29, began a desperate search for his mother.
Adam Fawell has today confirmed via Facebook that his mother was among the victims.
He wrote: "I'm really sad to say that my mum Wendy Fawell unfortunately has passed away as a result of the terror attack in Manchester.
"I want to say a massive thank you to all friends and family who have shared posts to try and find her and all the messages that have been sent.
"It really means a lot to us for all you have done. I can't thank you enough. RIP mum, you will be sadly missed."
Greg Mulholland, Liberal Democrat parliamentary candidate for Leeds North West, tweeted: "Heartbreaking that Wendy Fawell has been confirmed as a victim of the Manchester attack, deepest condolences & prayers with the family.