In Dublin, a small crowd gathered at the Irish Music Wall of Fame in Temple Bar to pay tribute to the late musician on Thursday.
It comes a day after the Irish star was pronounced dead at a residence in the UK's capital after officers responded to reports of an "unresponsive woman", London's Metropolitan Police confirmed Thursday.
The force - which did not name O'Connor, in line with UK policing protocols - said it was not treating the 56-year-old's death as suspicious. A coroner will eventually rule on the cause of death.
Political leaders and musicians like Bryan Adams and Cat Stevens have been honouring O'Connor since news of her passing emerged late Wednesday.
She shot to worldwide fame in the 1990s, best known for her cover of Prince's "Nothing Compares 2 U".