RIYADH, Saudi Arabia—Saudi Arabia and the U.S. are expected to agree to business deals and potential investments worth $300 billion over the course of U.S. President Donald Trump’s visit to Riyadh, solidifying the U.S.-Saudi commercial relationship as the kingdom’s economy cracks open.

The deals, ranging from defense to health care, coincided with the arrival Saturday of Mr. Trump in the capital, Riyadh. Mr. Trump, a real-estate developer turned politician, has sought to make business deals and job creation a central feature of his presidency and U.S.-Saudi ties.