Exhibit 99.1 Five9 Reports Full Year 2023 Revenue Growth of 17% to a Record $910 Million 2023 Enterprise Subscription Revenue Growth of 25$239 Million Q4 Record GAAP Operating Cash Flow of $37 Million SAN RAMON, Calif. - February 21, 2024 - Five9, Inc. (NASDAQ:FIVN), the Intelligent CX Platform provider, today reported results for the fourth quarter and full year ended December 31, 2023. Fourth Quarter 2023 Financial Results • Revenue for the fourth quarter of 2023 increased 15 ...