Gately was a vice patron of the charity Missing People (formerly National Missing Persons Helpline), supporting their Runaway Helpline service for young people. He was an ambassador for the Caudwell Children Charity in Stoke and on one occasion gave a private Christmas performance, raising thousands of pounds. Gately's family requested that donations be given to the charity instead of flowers sent to them after his death in 2009. This in turn raised thousands more pounds. On one visit to a hospital he met a terminally ill child who admired the jacket he was wearing, and Gately allowed her to have it.
Gately died at his home in Port d'Andratx, Mallorca, early on 10 October 2009. His body was discovered later in the morning. His death was later determined to have been caused by a pulmonary oedema resulting from an undiagnosed heart condition.
Gately's bandmates flew to Mallorca on 11 October 2009; The remaining members of Boyzone, Keith Duffy, Michael Graham, Ronan Keating, and Shane Lynch, issued a joint statement:
Fans responded with messages of sympathy on Twitter and Facebook. Thousands of pounds have been donated by fans to a Stoke-based children's charity which Gately had endorsed. Searches for "Stephen Gately" was said to have "risen exponentially" and remained at the top for several days after the singer's death and was later confirmed as being the most searched for topic on Google's UK site in 2009. The search term "Boyzone" also ranked highly, being separated from "Stephen Gately" only by second-placed searches for "Nobel Peace Prize" following a controversial award to US President Barack Obama. Boyzone's record catalogue was propelled back into the music charts. The single "No Matter What", on which Gately is a prominent vocalist, received heavy play on radio.
Boyzone's former manager Louis Walsh is quoted as saying: "We're all absolutely devastated. I'm in complete shock. I was only with him on Monday at an awards ceremony. We don't know much about what's happened yet. I only heard after The X Factor (UK television talent show on which Walsh is a judge) and we will rally around each other this week. He was a great man." Walsh dropped out of the live results show of The X Factor on 11 October 2009 as a direct result of Gately's death. Simon Cowell addressed the issue at the start of the programme. He said: "This is really, really tragic news I want to send out my condolences to the family, our thoughts are with Louis". That edition of the show attracted an "absolutely huge" audience which was said to have been seeking updates on the singer's death. Walsh also was absent from the second week of The X Factor which coincided with Gately's funeral,—later commenting: "I never want to watch the show at home again. I've been shouting at the TV all night"—at which Walsh was too upset to speak. My First Time, a stage show which was set to star bandmember Keith Duffy, was cancelled entirely. Duffy, Graham, Keating and Lynch had memorial "76 09" tattoos (Gately's birth and death years) inked on their bodies when they brought Gately's body home.
An article by Jan Moir in the Daily Mail on 16 October 2009 claimed: "Healthy and fit 33-year-old men do not just climb into their pyjamas and go to sleep on the sofa, never to wake up again. Whatever the cause of death is, it is not, by any yardstick, a natural one." She suggested that drugs and a "dangerous lifestyle" were to blame for Gately's death.