Background: The Kenya National Immunization Technical Advisory Group recommended introducing seasonal influenza vaccination for children aged 6–23 months, conditional on local evidence on feasibility, costs, and programmatic impact. Following a pediatric influenza vaccination demonstration project conducted in Kenya from 2019 -2021, we estimated the financial and economic costs of implementing a national program. Methods: We used WHO’s Seasonal Influenza Immunization Costing Tool to estimate five-year (2021-2025) national-level financial and economic costs of an influenza vaccination program under three facility-based strategies: (i) year-round, (ii) 4-month campaign, and (iii) campaign-to-year-round. Model parameters were obtained from Kenya’s 2019–2021 influenza vaccine demonstration project conducted in 4 sub-counties in Kenya, national vaccine program data, and publicly available sources. Cost data at the sub-county level were extrapolated nationally and presented in 2025 US dollars. Results: In the introductory year, total financial costs were highest for the campaign-to-year-round strategy at US$28.7 million followed by US$24.9 million for the year-round strategy, and US$21.4 million for campaign delivery. All strategies cost between US$17-20 million per year between 2022 and 2025. Overall five-year financial costs were highest for the campaign-to-year-round strategy (US$ 101 million) followed by campaign strategy (US$ 100 million) and year-round strategy (US$97 million). Overall five-year economic costs were highest for the campaign-to-year-round and year-round strategies (US$181-184 million) compared to the campaign strategy (US$136 million). Vaccine procurement accounted for 63-80% of total financial costs and nearly half of economic costs in the introductory year. Excluding vaccine procurement, the campaign strategy had the highest financial cost each year with the highest cost per dose (US$3.18 in 2021, US$1.26 thereafter) while year-round delivery achieved the lowest cost per dose (US$1.32 in 2021, US$0.09 thereafter). Conclusions:  Excluding the costs of vaccine, year-round and campaign-to-year-round pediatric influenza vaccination strategies achieved lower financial costs. Our findings suggest that, at current vaccine prices, implementing a universal influenza vaccination program for Kenyan children aged 6–23 months would require at least two-thirds of Kenya’s current national immunization budget, with certain strategies surpassing the budget. Decision makers may consider more targeted vaccination approaches focusing on pediatric subgroups at highest risk of severe influenza.