More than one million people in the North are now fully vaccinated, the region's Department of Health has said.
Around 70 per cent of the adult population have received both doses of the Covid-19 vaccine.
The milestone comes eight months after the first jab was administered in Northern Ireland.
Minister for Health Robin Swann described the vaccination programme as an “outstanding success”.
He added: “It has helped us take significant strides towards the more normal life that we all want to see return.
“Rolling out the vaccination programme has required a huge amount of hard work and dedication, so to all involved please accept my sincere gratitude.
“I appreciate the long hours you have worked to ensure that we could give the people of Northern Ireland protection from this virus.
“For all those who have already come forward for vaccination, thank-you. You have helped play your part in getting us to where we are. You have helped to protect yourself, those around you and our health service.”
The Ulster Unionist minister said there is a need to increase vaccine take-up rates in the coming days.
— Department of Health (@healthdpt) July 25, 2021
The Delta variant is driving up daily cases of the virus, which has also led to an increase in the number of people admitted to hospital.
“If we can make a concerted effort to increase vaccine uptake in the next week or so, this can help make a decisive difference in terms of preventing serious illness and hospitalisations,” Mr Swann added.
“Our regional vaccination centres are closing for first doses in less than seven days so please if you’re not vaccinated, make it your priority to get a first dose as soon as you can.”
The North's chief medical officer Dr Michael McBride said it was a life-saving vaccination programme.
“There are many people alive here today because they have been vaccinated,” he said.
“This virus is not going away and increasingly the only way we all get back to doing more of the things we want to do is for more of the population to be vaccinated.”
Patricia Donnelly, head of the Covid vaccination programme in Northern Ireland, said: “We are very pleased with the success of the programme but we do not take these milestone for granted.
“There has been a lot of hard work and determination behind this programme and we know we are not at the finish line yet.
“Uptake in the older age groups has been exceptional but only 56% of our under-30s have come forward to date.
“We do not want this age group to miss out. Time is running out in vaccination centres for first doses so if you have not already come forward, then please do so soon.
“Earlier this week we also announced that those young people who turn 18 on or before 31 October 2021 will be able to get vaccinated.
“If you’re in this group then you can simply go to one of the regional vaccination centres, or if you prefer you will shortly be able to make an appointment using the online system.”
A further 1,264 cases of Covid-19 were reported in Northern Ireland on Sunday.
Two further deaths of patients who had previously tested positive for the virus have also been notified.
In total, 2,204,177 vaccines have been administered.