This research was conducted to analyze the effect of knowledge management (X1) and organizational culture (X2) on transformational leadership (Y) with assertiveness (Z) as a moderating variable at PT. Alfa Karsa Persada KBN Marunda. The population in this study amounted to 130 people. Determination of the number of samples in this study using the slovin formula. The samples studied were some of the permanent employees at PT. Alfa Karsa Persada KBN Marunda totaling 99 people, the sampling method in this study is purposive sampling method of determining the sample by selecting certain samples that are assessed according to the objectives or research problems in a population. The type of data used in this study is primary data, where the data collection techniques are observation, interviews, and directly by distributing questionnaires. The data analysis method used Structural Equation Modeling (SEM). Structural Equation Modeling (SEM). The calculation phase uses Smart PLS 3.2.7 with 2 models, namely the Measurement Model (Outer Model) and Structural Model Testing (Inner Model). The results of this study indicate that knowledge management has a positive and significant effect on transformational leadership variables, organizational culture has a positive and insignificant effect on transformational leadership, assertiveness has a positive and insignificant effect on transformational leadership, assertiveness weakens the influence of knowledge management on transformational leadership, assertiveness can strengthen the influence of transformational leadership. organizational culture on transformational leadership.