Musk's attendance could be a sign of reconciliation in a turbulent relationship between the Tesla CEO and the US president.
Musk supported and funded Trump's election last year and became a close adviser to his administration early this year, leading the Department of Government Efficiency (DOGE) and overseeing cuts to federal funding and jobs.
But the two soon had a spectacular falling out.
The billionaire businessman took to social media to attack Trump's sweeping tax and spending bill as fiscally reckless, and said he planned to create a new political party.
Trump hit back threatening to cut off the billions of dollars in subsidies that Musk's companies received from the federal government.
The feud, along with Musk's far-right political rhetoric, hurt Tesla's brand image, sales and stock price, analysts have said.
Musk and Trump have rarely come together publicly since. Musk was last spotted shaking hands with Trump at a memorial for conservative activist Charlie Kirk in September.
Trump is hosting the Saudi de facto ruler as the latter seeks to rehabilitate his global image and deepen ties with Washington.
Others at the dinner included Portugal's soccer star Cristiano Ronaldo and Nvidia CEO Jensen Huang.
