This study was concerned with testing the effect of the interactive relationship between earnings management practices and tax avoidance activities and their impact on Firm Value. In order to achieve this, two models were developed for the study, where the first independent variable (earnings management) was measured through the discretionary accruals (Jones model), and the second independent variable (tax avoidance) was measured through the effective tax rate, and for the dependent variable (firm value), it was Measured by the Tobin's Q ratio, with the use of four controlling variables (company size, financial leverage, return on assets, and operating cash flow ratio). A sample of 70 Egyptian listed companies belonging to non-financial sectors. During the period from 2014-2018, the results of the study indicate the following: - There is a significant negative effect of earnings management practices on the Firm Value. - There is also a positive significant effect of tax avoidance activities on Firm Value. - There is a positive significant effect of the interactive relationship between earnings management and tax avoidance on Firm Value, which means that the interactive relationship between (earnings management and tax avoidance) on firm value affects more than the impact of each single variable on the firm value. Thus, the importance of the interactive relationship between earnings management and tax avoidance in affecting firm value becomes clear.