More than 200 mourners crammed into the South Lanarkshire Crematorium, in High Blantyre, yesterday for the service to celebrate the 59-year-old's life.
Mr Cusker, who lived in Cambuslang, was one of 10 people who died after a helicopter crashed into the Clutha pub, in Glasgow's Stockwell Street, on November 29.
Former housing officer Mr Cusker was pulled from the rubble alive and was conscious for days after the crash. However, he died last Thursday from his injuries after spending nearly two weeks in intensive care at Glasgow's Royal Infirmary.
Mourners comforted each other as they arrived for the funeral service.
Mr Cusker's wife Margaret McClemont, 58 and his son Kieran, 28, joined his step-children and grandchildren, for the touching humanist service.
Police Scotland Detective Inspector Una Maider, who is part of the major inquiry team investigating the crash and the family liaison team, were also in attendance.
Glasgow City Council leader Gordon Matheson and Lord Provost Sadie Docherty paid their respects, along with the Scottish Government's Community Safety Minister Roseanna Cunningham.
Pointing to his political roots, Mr Cusker's coffin was draped in a Soviet flag with a white rose on top, while Socialist anthem, The Internationale, was played as mourners arrived.
The coffin was carried into the building by his friends and colleagues.
During the service, mourners were told how Mr Cusker was born in Glasgow before the family moved to South Lanarkshire.
Mr Cusker, who married Margaret two years ago after they had been together for more than 20 years, was described as a family man who was intellectual and worked hard in his role as a housing officer in Cambus-lang, as well as enjoying taking holidays abroad.
His close friend Ian Kelly wept as he told stories about Mr Cusker's life and said: "Joe was a very proud Glasgwegian."
A poem read out by his step-daughter Tina included the words: "We will always remember you, we will miss you, dad, and we will always love you."
During the ceremony, mourners listened to You Don't Have to Say You Love Me by Dusty Springfield.