Continuous cultivation of farms has led to decline in soil fertility due to constant removal of nutrients leading to reduction of carrot (Daucus carota L.) yields. A field study was carried out at Egerton University, Horticulture Research and Teaching field in two seasons (October 2010 to January 2011 and February to May 2011) with the aim of investigating the effects of decomposed cattle bio-slurry manure on carrot growth and performance. The experimental design was a Randomized Complete Block Design (RCBD) with 3 replications. Treatments comprised four levels (0, 2.6, 5.2 and 7.8 t/ha) of decomposed bio-slurry manure. Growth, yield and quality parameters were recorded and used to discern the treatment effects. Application of bio-slurry manure generally improved growth, yield and quality of carrots. Application of 7.8 t/ha of bio-slurry increased yields by 8.8% in season 1 and 23.5% in season 2 compared to the control. Leaf numbers, plant height, dry weights of shoot and roots and root volume were also generally higher for the 7.8 t/ha treatment compared to other treatments. Total Soluble Solids of roots from plant treated with 7.8 t/ha were higher by 12.7% in season 1 and 13.2% in season 2 compared to the control. The study recommends 7.8 t/ha of bio-slurry manure for enhanced yield and quality of carrot.