The unit will conduct the high-speed transfer of digital breast screening images to the head offices of Action Cancer. Besides this, health check ups for men and support services will also be offered on board the unit, the first of its kind in Europe.
According to Action Cancer chief executive Robin McRoberts the unit was crucial to cancer prevention and early detection services because rates of the disease are set to increase by up to 54% over the next 20 years.
He said: "We believe it will make a dramatic impact on the provision of improved cancer services in Northern Ireland, ahead of many other countries.
"The new mobile service will enable Action Cancer to provide a comprehensive, effective and accessible regional service.
"It also offers cancer services for males and females of all ages right on their doorstep."
The unit also featured a new support scheme called the Listening Ear Service.
In addition complementary therapies will also be offered to cancer patients, their care givers and families onboard the unit that has been made fully accessible for people with disabilities by means of a wheelchair lift.
The bus was launched at Hillsborough Castle by television personality Gloria Hunniford, whose daughter Caron Keating died from breast cancer two years ago.
She said: "I am delighted to be here to see the Big Bus start its life-saving journey.
"It is a fantastic resource for the people of Northern Ireland and I believe it will not only bring vital early detection services to women and men, but it will help people affected by cancer with vital support and information when they need it most."
The bus is said to have been the result of six months of work with a £1.5 million investment in the first three years. About 200 site visits with the unit have been planned for the first year.
The unit will have links with health boards, community groups, GP practices, workplaces, schools and youth centers.
Geographical areas will be targeted where the cancer risk is highest and uptake rates for screening and primary care are lowest, with men and women both benefiting equally.
The new service is expected to bring lifestyle education, emotional support and life-saving cancer detection services to thousands of people annually.
Action Cancer Big Bus services manager Gale Sergeant said: "We will be bringing the Big Bus to 200 community groups and workplaces throughout Northern Ireland every year, spending a month at a time in each health board area."