Foreign Ministry spokesman Saeed Khatibzadeh told a news briefing in Tehran that the necessary framework for unblocking the assets has already been identified and agreed upon.
He said a high-level delegation from a regional country will be visiting Tehran this week to finalize the mechanism for unblocking what he called "significant assets", without mentioning the country's name.
Tehran has accused Seoul of freezing more than $7 billion in foreign exchange reserves under US pressure.
The issue has led to frayed ties between the two countries, spilling into different areas.
In January, Iran's Deputy Foreign Minister Ali Bagheri told his South Korean counterpart Choi Jong-kun on the sidelines of the Vienna nuclear talks that Seoul was "obliged" to release Iran's frozen assets, and that US sanctions cannot justify its non-payment.
The official announcement on Monday followed days of intense media speculations that frozen assets would be released and transferred to Iranian bank accounts on the pattern of the framework under which the UK released Iran's assets.
Reports are doing rounds that Iran's assets in South Korea would be unblocked in exchange for the release of three Iranian-Americans — Morad Tahbaz, Baqer Namazi, and Siamak Namazi — who are jailed in Iran.
Last month, the UK released $530 million it owed Iran for a canceled arms deal in the 1970s in exchange for the freedom of two British-Iranians jailed over espionage charges.
Iran has more than $100 billion in assets frozen in foreign countries, including South Korea, Iraq, Japan, and Canada, among others.
The funds were frozen soon after former US President Donald Trump withdrew his country from the 2015 nuclear deal and reimposed tough sanctions on Tehran.
According to sources, the deal to unfreeze assets in South Korea is unrelated to the Vienna talks, which have been suspended due to some key sticking points between Tehran and Washington.