The figure is down from 10 flags awarded last year.
Beaches with a Blue Flag demonstrate their commitment to protecting the coastal environment, water quality, safety, and access for all.
Keep Northern Ireland Beautiful have presented beach and marina operators with 14 national and 10 internationally-recognised awards.
Two marinas have also been awarded blue flags - at Ballyronan, County Londonderry, and Ballycastle, County Antrim.
Tony Wilcox, chairman of Keep Northern Ireland Beautiful, said: "Having Northern Ireland's world class beaches managed to such high standards is helping improve the quality of our lives as well as attracting visitors".
Forty-seven countries participate in awarding Blue Flags to more than 4,000 beaches and marinas worldwide.
The Department of Agriculture, Environment and Rural Affairs monitors identified bathing waters on 20 occasions during the annual bathing season, which runs from the 1 June until 15 September.
In 2016, Portstewart Strand in County Londonderry was awarded the accolade of Best Blue Flag Beach in the UK.
County Down: Cranfield West, Murlough, Tyrella
County Antrim: Portrush West Strand, Portrush East Strand
County Londonderry: Portstewart, Benone, Downhill
Twelve beaches were given the Seaside Award - the national standard for beaches across the UK.
This award guarantees a clean, safe, attractive and well-managed coastal environment with varied levels of facilities provided depending on the location of the beach.
Two Northern Ireland beaches have received the Green Coast Award, which recognises an agreement with the local community to protect and promote a natural beach environment, rather than developing visitor infrastructure.

Mohammed Allan, an alleged activist for the Islamic Jihad militant group, was on a respirator and was being given fluids, an Israeli hospital said.
His case is being seen as a test of a recent Israeli law authorising the force-feeding of hunger strikers.
Israeli doctors are challenging the law, which they say is unethical.
The Israeli Medical Association has described force-feeding as tantamount to torture and a violation of a patient's rights. It has urged doctors to refuse orders to perform the procedure.
Supporters of the law say force-feeding is necessary to save prisoners from death, and to discourage them from using hunger strikes as a tactic to end - or draw attention - to their detention.
It is not yet known if Mr Allan will be subjected to the controversial procedure, in which doctors forcibly insert a tube into the empty stomach. The decision could depend on his medical condition.
A statement from the Barzilai hospital, where Mr Allan is being treated, said his condition had deteriorated on Friday morning but remained stable.
"The treatment is being administered according the ethics committee guidelines and includes respiration and intravenous fluids and saline," a hospital statement said.
Jamil al-Khatib, a lawyer for Mr Allan, told the AFP news agency that he had heard his client had gone into a coma and that Israeli authorities were planning to force-feed him.
However, an Arab-Israeli MP, Osama Saadi, told the Associated Press news agency that Mr Allan was not being force-fed and was not in coma.
Mr Allan has been held without charge since November.

The SEP V fund will invest up to £20m in growth-stage technology businesses based mainly in the UK and Ireland.
It will also play "an active and supportive role" in their development.
SEP said investments in companies in other European countries would also be considered.
According to SEP, the fund was over-subscribed and closed above target.
SEP managing partner Calum Paterson said: "This is another great milestone for us and reflects extremely well on the calibre of our team.
"The new fund gives us a very strong platform to continue to invest in companies with world-class potential and we thank all of our investors for their support."
SEP portfolio companies currently employ more than 5,500 people and have aggregate revenues of more than £1bn.
They include Edinburgh-based travel search company Skyscanner and online car finance specialist Zuto, which is based in Manchester.
Non-UK companies in the portfolio include Berlin-based language learning company Babbel and Dublin-based e-commerce analytics company Clavis Insight.
SEP has 45 partners and employees across its Glasgow, London and Edinburgh offices.
Eight Northern Ireland beaches will proudly display international Blue Flags this summer.
[NEXT_CONCEPT]
A Palestinian held without charge by Israel has lost consciousness after nearly two months on hunger strike in protest at his detention.
[NEXT_CONCEPT]
Glasgow-based venture capital firm Scottish Equity Partners (SEP) has raised £260m for a new fund that will focus on high-growth technology companies.