'The Wanted' singer was diagnosed with an inoperable brain tumor in 2020.
In an Instagram post, Hardwick said he died on Wednesday with family by his side. Parker was a dad to two kids, 2-year-old daughter Aurelia and 1-year-old son Bodhi.
"It is with the heaviest of hearts that we confirm Tom passed away peacefully earlier today with all of his family by his side," she wrote. "Our hearts are broken. Tom was the centre of our world and we can't imagine life without his infectious smile and energetic presence. We are truly thankful for the outpouring of love and support and ask that we all unite to ensure Tom's light continues to shine for his beautiful children. Thank you to everyone who has supported in his care throughout, he fought until the very end. I'm forever proud of you."
Parker shared his devastating diagnosis in October 2020. He noted that though doctors told him his brain tumor was "inoperable," he wasn't giving up.
"I'm going to be here. I'm going to fight this," he wrote on Instagram.
Last January, the singer celebrated a "significant reduction" in his brain tumor.
"Friends, family and everyone on this journey with me- you have got me through my darkest days💪🏻💪🏻," he wrote on Instagram. "To everyone on here- your love, light and positivity have inspired me. Every message has not been unnoticed they have given me so much strength."
Ed Sheeran mourned the late star with a tribute on Instagram, writing, "So sad to hear of Tom's passing. Thoughts and love are with Kelsey, his children and his family. Very sad day, what a lovely guy x."
His bandmate, Siva Kaneswaran, Instagrammed on Wednesday, "Hey Tom, hope you’re having a blast up there. I am so grateful that I had a chance to witness your true courage. It has been a pleasure of my life Tommy Boy. Thank you for letting us see you light up the world. Talk to you soon and see you later. Love you brother x."
In an Instagram Story, One Direction's Liam Payne wrote, "I'm heartbroken to hear about Tom. He was so full of life and humour, and the memories I have of him will stay with me forever. Sending my thoughts out to his family and his brothers in The Wanted."
ET spoke to Parker in October and he talked about The Wanted reuniting for a charity concert and releasing their first single in seven years, as well as how he was doing amid his brain tumor battle.
"Well, it's been a really lovely because not only is it been a great distraction ... it's just been nice to just be around, love, support, and positivity, you know, because these symptoms come very easily and quickly drag you down," he said. "And you know, just the boys came around with just the right moment, really did to pull me up from the depths."