The tea industry is the foremost industrial cash crop in Kenya, contributing about 4% of the national gross domestic product and serving as a major source of foreign exchange, yet the financial performance of tea processing factories has been declining and payouts to farmers have fluctuated markedly from year to year. It has not been clear which firm-specific attributes drive these inconsistencies in the factories managed by the Kenya Tea Development Agency (KTDA), particularly in the Nyanza region. The purpose of this study was to establish the effect of firm characteristics, expressed through liquidity, leverage and firm size, on the financial performance of KTDA-managed tea processing factories in the Nyanza region, Kenya, and to determine the moderating effect of firm age on this relationship. The study was anchored on the Organizational Life Cycle Theory and supported by the Liquidity Preference Theory, the Capital Structure Theory (Modigliani and Miller Theorem) and the Economies of Scale Theory. A descriptive research design was adopted and a census of the 15 KTDA-managed tea processing factories in the Nyanza region was conducted, yielding a balanced panel of 75 factory-year observations over the period 2019 to 2023. Secondary data was collected using a data collection sheet from audited financial statements, KTDA records and Tea Board of Kenya filings, and was analysed using descriptive and inferential statistics with the aid of R Studio. Financial performance was measured by return on assets (ROA), which averaged 5.37% over the study period. Correlation analysis returned strong, positive and significant relationships between financial performance and liquidity (r = 0.847, p = 0.002), leverage (r = 0.856, p = 0.001), firm size (r = 0.864, p = 0.000) and firm age (r = 0.831, p = 0.003). Guided by the Hausman test (χ² = 24.85, p = 0.0001), a baseline fixed effects panel regression with clustered robust standard errors was estimated, and the results showed that firm size had a positive and significant effect on ROA (β = 0.00002, p = 0.0894), leverage had a negative and significant effect (β = -0.0045, p = 0.0694), and liquidity had a positive but statistically insignificant effect after clustering (β = 0.0038, p = 0.1812). The moderated fixed effects model showed that firm age had a positive and significant conditioning influence on performance (α₄ = 0.000214, p = 0.0129) and that the interaction term between firm size and firm age was positive and statistically significant (α₅ = 0.000002, p = 0.0491), confirming that firm age significantly moderates the relationship between firm characteristics and financial performance. The study concluded that firm characteristics significantly influence the financial performance of KTDA-managed tea processing factories in the Nyanza region and that firm age strengthens the payoff from asset expansion. The study recommends that factory management should leverage accumulated experience and institutional knowledge, maintain adequate liquidity, adopt prudent borrowing strategies and pursue strategic expansion that exploits economies of scale, while KTDA and policymakers should design interventions that address the systemic decline in regional profitability observed over the study period.