Transport, schools, hospital and local government have all been affected by Wednesday's walkout.
Rallies and demonstrations took place across Northern Ireland, with picket lines formed outside public sector workplaces.
"I think the government has taken enough off us at this stage," one Belfast member of the union NIPSA told UTV, as colleagues chanted anti-cuts slogans to the blaring of car horns by passing traffic.
This isn’t public sector against private sector. We’re not just standing here for our own pay and our own pensions – we’re standing here for the people we provide services for as well.
NIPSA striker
Another union member added: "At the end of the day, this is our future - this is not only my future, it'll be my children's future as well."
All public transport has been suspended for the day, with police opening bus lanes - except those on motorways - for use by all drivers, in a bid to alleviate any congestion.
All 1,200 schools in Northern Ireland have faced some level of disruption, with many closing their doors to pupils after teaching unions backed the industrial action.
Many hospital appointments and surgical procedures have been postponed, although GP and Emergency services are in operation and ambulances are running.
Union leaders have backed the decision to strike as legitimate and necessary to protect both the rights of workers and the quality of public services and say the message must be heard.
We are the many – they are the few. This is what democracy feels like. This campaign does not end today.
Peter Bunting, NIC-ICTU
As an estimated 10,000 people gathered at one of the main rallies outside Belfast City Hall, Peter Bunting addressed the crowds on behalf of the Northern Ireland Committee of the Irish Congress of Trade Unions.
"Rather than complain about today, the business community should consider the long term," he said.
"The loss of one day's pay for going on strike is worth it.
"Because if the Tories get their way, public sector workers will have one day's pay docked every single month - forever - to pay off the bankers' debt."
General Secretary of the union Unison, Patricia McKeown, has already said members were forced into taking action and making a firm stand.
"Many of the low paid women workers taking strike action are not even in a pension scheme," she said.
"This is a real indication of the strength and depth of feeling for our welfare state and our public services."
The mass walkout - involving an estimated two million people across the UK - comes just a day after the Chancellor outlined his Autumn Statement to Westminster MPs.
Among the plans, George Osborne proposed a 1% pay rise cap on public sector workers for two years, after the current two-year pay freeze ends, and bringing forward to 2026 the date on which the state pension age will increase from 66 to 67.
Unions say that has only heightened the current dispute.
The Government should re-examine the case for strengthening the law to ensure strikes can only go ahead if 40% of the balloted workforce have voted in favour of action, as well as simple majority.
Kirsty McManus, CBI
Some private sector workers have criticised the industrial action though, over the impact of disruption on businesses and families.
Assistant Regional Director at CBI Northern Ireland, Kirsty McManus, said: "It's really disappointing that this strike has gone ahead when some of the unions involved haven't even managed to secure a clear mandate.
"Not only is this strike a major headache for parents whose children's schools have closed, it will cost the economy dearly."
Check out pictures from the pickets in our gallery Wednesday Walkout.