The experiment was conducted to compare the growth of mushroom (Pleurotus ostreatus) using different substrates. The substrates that were used to grow the mushroom includes; a mixture of sawdust (5kg) + wheat bran + CaCO3, a mixture of sawdust(5kg) + bio fertilizer + CaCO3, a mixture of cassava peel (5kg) + wheat bran + CaCO3 and a mixture of cassava peel (5kg) +bio fertilizer + CaCO3. The experiment were carried out using Completely Randomized Design (CRD) of four treatments and twenty replicates (5 replicates per treatment). The results of the indoor mushroom cultivation experiment showed that, for the first flush, the mean fresh weight varied from 60g for mixture of sawdust and wheat bran to 30g for mixture of sawdust and biofertilizer. For the second flush, the mean fresh weight varied from 48g for mixture of sawdust and wheat bran to 21g for mixture of sawdust and bio fertilizer while the dry weight for the first flush ranged from 7g for the mixture of sawdust and wheat bran to 3g for the mixture of sawdust and bio fertilizer. For the second flush, the mean dried weight ranged from 4g for the mixture of sawdust and wheat bran to 1g for the mixture of sawdust and bio fertilizer. The colour of mushroom fruits for the mixture of sawdust and wheat bran was light yellow while the colour of mushroom fruits for the mixture of sawdust and bio fertilizer was white colour. The mixture of cassava peel and wheat bran did not support the growth of mushroom while the mixture of cassava peel and bio fertilizer did not produce Pleurotus ostreatus rather a different species of mushroom. Considering all the treatments investigated, the mixture of sawdust and wheat bran substrates is recommended as the best and fastest medium for the indoor cultivation of Pleurotus ostreatus.