Pigeon pea (Cajanus cajan) is an important crop in dry land and semiarid regions and is a supplementary source of dietary protein for the economic resource-constrained farmers. The aim of this research was to evaluate growth parameters of 12 vegetable pigeon pea cultivars at two locations in eastern Kenya. The number of days from planting to flowering, plant height, primary and secondary branches, and pod length and width were quantified in experimental plots in a randomized complete block design with three replications. Significant differences (P < 0.01) in days to 50% and 70% flowering (DTF) and plant maturity (DTM), respectively, were recorded among cultivars at both locations. The average plant height was significantly (P < 0.05) greater at Kiboko than at Kambi ya Mawe. The number of DTF and DTM were also greater at Kiboko than at Kambi ya Mawe site, because of supplemental irrigation. Similarly, mean pod length and width at Kiboko location exceeded that at Kambi ya Mawe by 6% and 8%, respectively. Positive and significant (P < 0.05) correlation coefficients between grain yield and pods per plant were observed, indicating that pod number is a useful indicator of yield potential of vegetable pigeon pea. The cultivars ICEAP 00068, ICEAP 00540, ICEAP 00554, ICEAP 00902, KAT 60/8, and MZ 2/9 were identified for high-yield potential under rain-fed conditions, whereas ICEAP 00902, ICEAP 00068, ICEAP 00557, ICEAP 00554, KAT 60.8, and MTHAWAJUNI showed the greatest potential when supplemental water applications were made. The cultivars KAT 60/8, ICEAP 00068, ICEAP 00554, and ICEAP 00902 were suitable for production under both rain-fed conditions and additional water applications. Yield potential of pigeon pea in the dry regions can be greatly enhanced by using cultivars with good plant growth characteristics and shoot density.