Tom, who was diagnosed with stage 4 glioblastoma back in October 2020, died Wednesday with his family by his side ... according to his wife, Kelsey.

Kelsey says Tom fought to the end, sharing, "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."

As we reported ... Tom was recently confined to a wheelchair while undergoing cancer treatments at a clinic in Spain, which specializes in his particular type of brain cancer.

Tom got treatments for 3 weeks and was able to rejoin the band in February for an emotional reunion, also appearing on stage at a U.K. concert and performing from a gold throne.

Born and raised in Bolton, England, Tom learned to play the guitar when he was 16 years old ... eventually dropping out of school to pursue his singing career before joining The Wanted way back in 2009.

Tom is survived by Kelsey and their two children, 2-year-old Aurelia and 1-year-old Bodhi.

He was only 33.