Boeing Co. completed a deal to sell 80 jetliners to Iran, the first major agreement between a U.S. company and the Islamic Republic since the election of Donald Trump, a critic of closer links between the countries.

The first Boeing 777-300ER long-haul planes would be delivered to Iran Air in 2018 under the deal announced Sunday that carries a list price of $16.6 billion before discounts, though the sale still requires approvals from the U.S. government and lawmakers.

Planned...