Exhibit 99.1 Contacts Ultragenyx Pharmaceutical Inc. Investors Joshua Higa ir@ultragenyx.com Ultragenyx Reports First Quarter 2024 Financial Results and Corporate Update First quarter total revenue of $109 million, Crysvita® revenue of$83 million and Dojolvi® revenue of $16 million Reaffirmed 2024 expected total revenue guidance between$500 million to $530 million, Crysvita revenue of$375 million to $400 million, and Dojolvi revenue of$75 million to $80 million Presented positive interim Phase 1/2 data ...