Global hotel companies are establishing new beachheads in Iran, betting that lifted sanctions against the Middle East nation will spark a jump in tourism and business travel after decades of economic isolation.

Spanish operator Melia Hotels International is planning to open a 319-room hotel next year on the Caspian Sea. French group Accor Hotels, which opened two hotels near the Tehran airport last autumn, is establishing a joint-stock company in Iran through which it will partner with local groups to manage hotels. Abu Dhabi-based...