The study was conducted to assess the “Effect of Tectona grandis Biochar on Soil Quality Enhancement and Yield of Cucumber (Cucumis sativus L) in highly weathered Ultisol , Southeastern Nigeria” , Southeastern Nigeria. The study was laid out as a randomized complete block design (RCBD) with five treatments (0 t ha−1, 2.1 t ha−1, 3.4 t ha−1, 4.7 t ha−1 and 6.0 t ha−1of biochar rates) and four replications. Data were collected from both soil and plant properties. Soil samples (0 to 20 cm) were collected before and at harvest from different plots for soil physical and chemical analyses. Results showed significantly increase (P<0.05) in soil physical properties (bulk density and hydraulic conductivity), chemical and exchangeable bases (pH, N, P, K, Ca, Na, Mg, CEC and BS) under field conditions in response to application of different rates of biochar, and was consistent with the plots amended with biochar relatives to control plots. Biochar applied at 4.7 t ha-1 resulted to the highest significant improvement (P<0.05) in all the agronomic parameters compared to other biochar application rates with biochar applied at 3.4 having the highest agronomic efficiency of 96.2%.