The Pakistani military said in a statement on Tuesday the surface-to-surface Shaheen II missile was tested successfully.
It stressed the system was developed by Pakistani scientists and engineers and could carry all types of warheads up to 2000km.
There was no immediate confirmation of the capabilities of the missile. India, which has its owns missile development programme, offered no immediate response to the news.
Pakistan says its weapons programme is a response to that of nuclear-armed rival India, with which it has fought three wars since both countries won independence from Britain in 1947.
Islamabad said it had informed neighbouring countries about the test as a "confidence-building" measure.
Pakistan says the new missile exceeds the 1500km reach of the Ghauri, previously its longest-range missile, which some experts say was developed with North Korean help.
The test of the Shaheen II comes amid intense scrutiny of Pakistan's nuclear programme after revelations that its scientists sold nuclear secrets to Iran, North Korea and Libya.
Islamabad says the aim of the test is deter aggression and "prevent military coercion".
"Our strategic force goals are guided by the concept of minimum credible deterrence and that's why we have to test these missiles from time to time," said Foreign Ministry spokesman Masud Khan on Monday.
India and Pakistan had a policy of informing each other ahead of missile tests, added Khan.
He said the aim of the test would be to ensure the "reach" of the missile was sufficient to deter aggression and "prevent military coercion".
India concluded a deal last week to buy an Israeli Phalcon airborne radar system, which Pakistan says will threaten its security and require steps to keep a balance between the two countries.
The Phalcon system can detect aircraft hundreds of kilometres away, can intercept radio transmissions and put large parts of Pakistan under Indian surveillance, including disputed Kashmir, which has been the trigger for two of the rivals' three wars.
But the arms disagreement has not stopped a thawing in relations that has led to a reopening of air, bus and rail links. The two countries are due to hold peace talks in May or June on all issues in dispute, including Kashmir.