The Vatican and Oman established diplomatic relations on Thursday, read a joint statement, in a move that comes three months after a visit by Pope Francis to the Gulf.
In a development that marks a further widening of the Holy See's official relations with the Muslim world, both sides said they wanted to promote mutual understanding and cooperation, and that ambassadors would be named.
The Vatican, a sovereign city-state surrounded by Rome, now has diplomatic relations with every country on the Arabian Peninsula except Saudi Arabia.
Oman, a Sultanate, is predominately Muslim, like the other countries on the peninsula.
There are currently 12 Catholic priests working in four parishes in Oman and the local population of nearly 4.5 million people includes a "significant number of foreign workers," the statement said.
The Vatican hopes that with the upgrading of relations, the Church could continue to contribute to the social well-being of the country, the statement added.
Pope Francis visited Bahrain in November, his second visit to the Gulf since becoming pope in 2013. His first visit was to the United Arab Emirates (UAE) in 2019.
In both places, he attended inter-religious meetings to promote dialogue among faiths.
Oman's parishes are part of the Apostolic Vicariate of Southern Arabia, which is based in Abu Dhabi.
Most of the country's Catholics are foreign workers from elsewhere in the Middle East, the Philippines, India and Pakistan, the statement said.
Kuwait was the first Gulf country to establish diplomatic relations with the Holy See in 1968. Thirty years later, the Vatican established ties with Yemen, followed by Bahrain in 2000, Qatar in 2002 and the United Arab Emirates in 2007.
There are about 3.5 million Christians – some 75% of them Catholic – in the Gulf, the birthplace of Islam.