The summit on 17 and 18 June is being hosted by Prime Minister David Cameron at Lough Erne in Co Fermanagh and will be attended by some of the world's most powerful leaders.
A number of organisations, including trade unions and campaign groups like Amnesty International and Friends of the Earth, have announced they will gather in Belfast on Saturday 15 June to "challenge the agenda" of the G8 delegates.
The protest committee said: "Civil society organisations have come together to offer people an opportunity to challenge the policies and priorities of the G8 leaders who meet in Northern Ireland in June 2013.
We will co-ordinate a festival of events to coincide with the G8 summit, including a major public demonstration in Belfast calling for a fairer world.
"Our organisations represent many different interests but we are united in a commitment to the creation of a world that is fair and just for all. We believe that achieving social, economic and environmental justice must be central to political decision-making."
Other events, including one in Botanic Gardens, will also take place that day.
It was revealed last week that US President Barack Obama and First Lady Michelle Obama will begin their visit to NI for the G8 in Belfast.
The trip will be President Obama's first to the region. Two years ago, he travelled to the Republic and visited both Dublin and his ancestral home of Moneygall in Co Offaly.
A massive security operation involving thousands of police officers will be in place around the G8 conference with protests also likely to be held in Fermanagh.
Meanwhile, research from Barclays has shown that local businesses expect the G8 conference to bring a cash boost of up to £40m to Northern Ireland.
It said 84% of companies think it will bring benefits for them while two thirds expect it to boost the economy - with potential for long-term growth in tourism and exports.
Secretary of State for Northern Ireland Theresa Villiers said: "This important report demonstrates that the Prime Minister's decision to host the G8 Summit in Fermanagh will provide a major economic boost to Northern Ireland.
"It shows that the benefits of Northern Ireland hosting the summit will be realised both in the short term and through a positive longer-term legacy, by helping increase inward investment."