Exhibit 99.1 Investor Relations News from Aon Aon Reports First Quarter 2025 Results DUBLIN - April 25, 2025 - Aon plc (NYSE: AON) today reported results for the three months ended March 31, 2025. | | | First Quarter 2025 | | | --- | --- | --- | --- | | | 2025 | 2024 | Change | | Total revenue | $4,729 |$4,070 | 16% | | Organic revenue growth (Non-GAAP) | | | 5% | | Operating income | $1,461 |$1,465 | —% | | Adjusted operating income (Non-GAAP) | $1,816 |$1,615 | 12% | | Operating margin | 30.9% | 36.0% ...