Mr Radich died yesterday afternoon in Dunedin Hospital after he had suffered a heart attack on Saturday.
He was 70.
Mr Radich was the 59th mayor of Dunedin, leading the city from 2022 until the election in October last year.
He was re-elected as a city councillor, which followed an earlier stint from 2019 to 2022.
A by-election at the Dunedin City Council will be needed to replace him.
Dunedin Mayor Sophie Barker said Mr Radich’s mayoralty would be remembered for his dedication to advocating for the city’s new hospital to be built at a suitable size.
"The end result — that all 11 floors of the inpatients building are being built on the former Cadbury site as promised — is due in no small measure to Jules’ tireless advocacy", she said.
Ms Barker said she was deeply saddened by Mr Radich’s death.
"Our thoughts, deepest love and sympathies are with Jules' family and friends, and the city’s flags fly at half-mast in honour of a respected colleague, leader and friend."
Deputy mayor Cherry Lucas first had the role under Mr Radich.
"His unwavering fight for the Dunedin hospital was his most significant achievement during his mayoralty", Cr Lucas said.
"I admired how he put his ego in his back pocket when he lost the mayoralty in 2025, and turned up with his usual smile on his face and twinkle in his eye, willing to serve the people of Dunedin."
Cr Brent Weatherall said he considered Mr Radich a dear friend.
"He wore the mayoral chains with pride, immense pride, and I just feel so sad for his family."
Cr Mandy Mayhem said she had known Mr Radich all her life.
"We mourn a friend and workmate taken too soon", she said.
Cr Christine Garey said his death was a huge shock for everyone.
Several new councillors said Mr Radich had been welcoming of them.
Cr Andrew Simms said the pair were adversaries during the mayoralty campaign, but when they were both elected as councillors "Jules immediately put the campaign aside and offered me friendship and advice".
"This struck me as the measure of Jules as a person and a measure of his generosity of spirit."
Cr John Chambers said Mr Radich was keen to help new councillors understand the issues and how the council functioned.
Cr Mickey Treadwell said he was generous with his time and collegial.
"He was something of a biscuit connoisseur, like most councillors, and he liked to vigorously debate the merits of the Griffins’ lemon creme between meetings."
Cr Russell Lund said he was cheery and likeable.
"He cared deeply about all of Dunedin and there is no better example of this than with his strenuous efforts to get a feasible and technical wastewater resolution for the people of South Dunedin."
Cr Doug Hall said he approached public service with a practical, solutions-focused mindset.
Business South chief executive Mike Collins said Mr Radich engaged with the business community through periods of challenge and transition.
"He held a clear belief in the importance of supporting business growth and employment, recognising the importance of strong partnerships, and bringing his own experience and understanding of business and investment to his approach to leadership."
Minister of Health Simeon Brown said he was sad to hear of Mr Radich’s death.
"Jules was a staunch advocate for Dunedin and for the construction of the new Dunedin hospital, which is now under way."
Dunedin MP Rachel Brooking said he was approachable, and Taieri MP Ingrid Leary said his South Dunedin advocacy showed leadership.
— Additional reporting by Tim Scott, Matthew Littlewood and Ruby Shaw
