This means the NI city is even more gridlocked than London, Birmingham, Leeds and Glasgow - cities with vastly higher populations.
Delays in traffic in Belfast now amount to over four days across the year.
The statistics - compiled from the satnav firm TomTom's traffic data - also show that congestion on secondary roads is worse than on main roads.
Commuters are spending on average eight working days a year stuck in traffic on those roads.
The global traffic index, which compares travel times during non-congested hours with travel times in peak hours, also reveals which are the Top Ten most congested cities in the UK in 2013.
The Top Ten is as follows:
1 Belfast 36%
2 London 34%
3 Edinburgh 34%
4 Bristol 32%
5 Brighton and Hove 31%
6 Manchester 26%
7 Leeds 26%
8 Sheffield 26%
9 Liverpool 25%
10 Nottingham 25%
Meanwhile, the latest figures released by the Department of Regional Development have revealed that over half of people travelling into Belfast in the morning peak time are using public transport, walking or cycling.
The figures were revealed in a report into the impact of the Belfast on the Move initiative over the last two years.
The report found that there has also been an increase of over 2,000 more people entering the city centre in the morning rush hour.
An increase of around 19% in the number of cyclists and a 12% rise in number of pedestrians travelling into the city during that time was also recorded.
Trains and buses also noted an increase - a 36% jump in the number of people using the morning trains and a rise of 40% in daily usage of bus based Park and Rides.
According to the DRD, morning peak traffic flows have been reduced by around one third in the city centre due to the Belfast on the Move initiative.
There are around 11,000 fewer vehicles in the core city centre streets each day which is a reduction of some 16% since 2010.
However, 500 more parking spaces were used on weekday mornings and over 1,000 more on Saturday mornings.
Transport Minister Danny Kennedy said: "The changes made to the streets in Belfast city centre have made travel by public transport, walking and cycling an attractive alternative to travel by private car.
"I am very pleased to see that more people are now choosing to travel into Belfast city centre by bus, train, walking and cycling on a daily basis."
Despite the fact there are more people are coming into the city centre in the morning peak, there are now fewer vehicles on Belfast's city centre streets each day, with the associated reductions in traffic flows through inner city residential areas. This has improved the environment for shoppers, workers, local residents and visitors.
Danny Kennedy, Transport Minister
"As a result of the project some of the `through traffic` which formerly used the city centre streets has re-routed to more strategic roads including Westlink, where traffic flows have increased by about 6,000 vehicles per day," the Minister explained.
"I am pleased that the number of cars parking in Belfast city centre has increased by more than 500 on weekday mornings and by more than 1,000 on Saturday mornings.
"There are many positive outcomes from the project, not least the increased use of public transport in and around Belfast city centre. My Department's recent investment in new trains and Park & Ride facilities, for example, has also undoubtedly played a part and this further supports the case for continued investment in our public transport system."