The study examined the effect of Accounting Information Systems on the financial performance of listed healthcare firms in Nigeria. The specific objective was to examine the effect of accounting software usage, cost of accounting software and accounting software investment intensity on the return on asset of listed healthcare firms in Nigeria. This study utilized an ex-post facto research design. The population included seven healthcare firms listed on the Nigerian Exchange Group as of December 31, 2023, with a final sample size of five firms selected through purposive sampling based on the availability of consistent financial data from 2014 to 2023. Secondary data were collected from the annual reports of these firms for a period of ten years, from 2014 to 2023. Descriptive statistics was used to summarize the dataset while panel least square regression with white period standard errors was used to test the hypotheses at a 5% significance level. The findings revealed that: accounting software usage has a non-significant positive effect on the return on assets of listed healthcare firms in Nigeria (β = 0.046449; p = 0.4411); cost of accounting software has a significant positive effect on return on assets of listed healthcare firms in Nigeria (β = 0.031437; p = 0.0002); accounting software investment intensity has a significant negative effect on return on assets of listed healthcare firms in Nigeria (β = -0.218236; p = 0.0000). In conclusion, even though accounting software usage alone does not lead to significant improvements in ROA, strategic investments in quality software can yield positive outcomes. The study recommends that management of Listed Healthcare Firms should focus on providing additional training to staff to enhance the effectiveness of software utilization in order to ensure that the benefits of the software are fully realized and integrated into broader business operations.