Abstract: Scarcity of seeds of forage legumes has continued to plague the pasture industry in Nigeria and there is a serious need to tackle this challenge, hence this study was initiated. The experiment entailed field trials that were conducted to evaluate the response of seed yield and yield attributes of lablab (Lablab purpureus L. Sweet) to phosphorus application and cutting treatments. The treatments were composed of factorial combinations of four rates of phosphorus application (0, 12, 24 and 36 kg P ha-1), two cutting heights (10 and 20 cm) as the main plot and four cutting ages (6, 12, 18 weeks and at maturity) as the sub-plot a split plot design with three replications. Cutting lablab at 6 weeks or at maturity produced 44.7 and 63.0% higher seed yield than cutting at 12 weeks. Cutting at 20 cm height produced 23.8% heavier seeds than cutting at 10 cm in 2007. Most seeds per pod, heaviest and longest pods were obtained when lablab was cut at either 12 weeks or at maturity. Phosphorus application rate of 12 kg P ha-1 increased 100-seed weight (4%) while cutting lablab to a 20 cm height rather than to 10 cm stubble height produced significantly higher 100-seed weight. The heaviest 100-seed weight was produced with a combination of 12 kg P ha-1 application rate and a 20 cm cutting height. Lablab could be developed as a ley pasture crop in the Nigerian farming systems to enhance its usefulness to livestock.