The study was conducted to find out the effect of principals' mobilisation of financial resources on teachers' integration of ICT in secondary schools in Nairobi City County, Kenya. In particular, it explored the relationship between principals' efforts to mobilise financial resources from alumni networks, parents' associations, foundations, faith-based organisations, and corporate entities and teachers' ICT integration outcomes. The study was descriptive and survey-based on Resource Dependence Theory with a target population of 142 principals, 17 sub-county officers and 2,955 teachers. The teacher sample of 296 respondents was drawn using stratified random sampling of the nine sub-counties in the county with proportional representation from public and private secondary schools, while the principals and Sub-County Directors of Education (142) were sampled using census sampling. A total of 281 teachers (94.9%) out of 296 sampled teachers returned the questionnaires that were usable for the final analysis, 126 principals (88.7%) out of 142 sampled principals and 12 sub-county officers (70.6%) out of 17 sampled sub-county officers. Data collection techniques used were questionnaires, interviews, and document analysis. Factor analysis and Cronbach's alpha values greater than 0.7 were used to confirm validity and reliability. Results showed that the principals' mobilisation of financial resources (r = 0.721; β = 0.199; p = 0.006) significantly influenced the integration of ICTs, and the overall effectiveness of principals' mobilisation of financial resources was very low (mean = 2.18, SD = 1.14) across all stakeholder categories. The correlation coefficient (r) showed that there was a strong positive relationship between financial mobilisation and teachers' ICT uptake. The regression coefficient (β) was used to show the strength of the influence, while the significance value (p < 0.05) showed that this relationship was statistically significant and not likely to be due to chance. The overall level of ICT integration was very low (mean = 2.07, SD = 1.16), and the lowest scores were for the use of instructional technology. The study concludes that principals' mobilisation of financial resources is a key but underperforming factor in the integration of ICTs, and that the failure to mobilise financial resources is related to principals' lack of preparation in stakeholder engagement, competing administrative demands, underdeveloped alumni networks, and stakeholder economic constraints. The study suggests that principals should design multi-stakeholder engagement strategies, formalise alumni associations, design attractive funding proposals, and introduce transparent resource tracking systems, and that policymakers should provide professional development on stakeholder engagement, design matching fund mechanisms, and create county-level coordination platforms to improve financial resource mobilisation and enhance the integration of ICT in secondary schools