The move marks a significant escalation from the short-range tests Pyongyang has conducted since May.
The North's Academy of Defence Science succeeded in test-firing the "new-type SLBM Pukguksong-3" in the waters off Wonsan Bay of the East Sea on Wednesday, Korean Central News Agency (KCNA) reported, adding that the missile was fired "in vertical mode".
"The test-firing scientifically and technically confirmed the key tactical and technical indexes of the newly-designed ballistic missile and had no adverse impact on the security of neighbouring countries," KCNA said.
"The successful new-type SLBM test-firing comes to be of great significance as it ushered in a new phase in containing the outside forces' threat to the Democratic People's Republic of Korea and further bolstering its military muscle for self-defence," added the report.
According to South Korean officials, the missile flew about 450 km and reached an altitude of 910 km before landing in the sea. That means the missile flew twice as high as the International Space Station, but previous North Korean tests have gone higher.
North Korean leader Kim Jong-un sent "warm congratulations", Yonhap news agency reported citing KCNA, suggesting he did not attend the testing.
Wednesday's launch was the North's 11th weapons test so far this year and the first SLBM test since August 2016, when it test-fired a Pukguksong-1 ballistic missile off the east coast, which flew about 500 km. During the previous 10 rounds of tests, Pyongyang fired only shot-range projectiles.
US President Donald Trump earlier played down the North's weapons tests involving short-range projectiles, saying that Kim was not breaking an agreement that they agreed in their summit in June last year. Trump has not commented on the latest SLBM testing.
Along with its intercontinental ballistic missiles (ICBM), the North's SLBM programme is considered one of the biggest threats to the US and its allies, as it could extend the range of the North's nuclear missiles and such a missile is hard to detect in advance before it emerges from the water.
Before the missile test, North Korea and the US confirmed that preliminary nuclear talks would take place "within the next week".
The US State Department responded to the test by calling on Pyongyang to "refrain from provocations" and "remain engaged in substantive and sustained negotiations" aimed at bringing denuclearization.
( With inputs from IANS )