Female officers will be able to wear a headscarf under their caps or berets, provided it is plain and is the same colour as the uniform.
Headscarf bans on university campuses and state institutions - except for the judiciary, military and police - have also been lifted in recent years.
The garment has been controversial in Turkey for years. Secularists regard it as a symbol of religious conservatism.
Since the 1920s, Turkey has had a secular constitution with no state religion.
The opposition have accused President Recep Tayyip Erdogan and his Islamist-rooted Justice and Development Party (AKP) of trying to reinterpret secularism.
However, public debate has also evolved to accept the hijab as an expression of individual liberties, correspondents say.
No strong opposition has been voiced against this latest move.
President Erdogan has long embraced Turks' right to express their religious beliefs openly, but he says he is committed to secularism.
In 2010, the country's universities abandoned an official ban on Muslim headscarves.
Three years later, women were allowed to wear headscarves in state institutions - with the exception of the judiciary, military and police. That year, four MPs wore headscarves in parliament.
Most people in Turkey are Sunni Muslims.

The story of Akong Tulku Rinpoche was screened at the Samye Ling site he founded in Eskdalemuir.
A Remarkable Life covers everything from his birth in Tibet in 1939 to his murder in China in 2013.
Shortly before his death, he authorised the film to be made which was given its premiere in southern Scotland.
Akong Rinpoche was installed as abbot of a monastery in eastern Tibet at the age of just four having been identified as the reincarnation of the previous abbot.
When he was 19, with China having occupied Tibet and tensions between the countries at their height, he joined a freedom walk over the Himalayas to India.
It took 10 months and of the 200 people who started, only 15 survived.
Akong eventually made his way to the UK in 1959 and acquired an old farmhouse at Eskdalemuir where Samye Ling was founded in 1967.
The film's executive producer Vin Harris told BBC Radio's Good Morning Scotland programme: "I think they travelled around lots of places, there was a story that it kind of reminded them of Tibet.
"There was someone there who was running a spiritual centre and he was ready to move on so they basically took it over.
"They were very much welcomed, particularly in Dumfries, Rinpoche made his family life there and had very good friends here."
Samye Ling was the first Buddhist monastery to be founded in Europe and students later included David Bowie and Leonard Cohen.
It has now grown into a large complex for the study and teaching of Buddhism, with a vast temple at its heart.
From there, Akong spearheaded a range of projects including  ROKPA International, which carries out humanitarian work in Tibet, Nepal, India and Africa.
It was while in China in October 2013 that he was murdered, aged 73, but before his death he authorised the film of his life to be made.
Its premiere at Samye Ling was attended by the current abbot, Akong's younger brother Lama Yeshe Losal Rinpoche.
"We feel that the film is more a message of hope actually - a celebration of his life," Mr Harris said.
"It kind of focuses on the fact that putting compassion into action, rather than being a kind of luxury, is so effective.
"We look at what, as a refugee, he achieved - setting up centres all over the world and helping thousands and thousands of people without compromising that value of compassion."
Turkey has lifted a ban on policewomen wearing the Islamic headscarf.
[NEXT_CONCEPT]
A feature-length documentary film about the founder of Europe's first Tibetan Buddhist centre in Dumfriesshire has staged its world premiere.