In this paper, we construct a generalisation of Ostrowski’s type inequalities with the help of new identity. By using this identity, we construct further results for ģ^'∈L^1 [c ̇,d ̆ ],ģ^'∈L^2 [c ̇,d ̆ ],ģ^''∈L^2 [c ̇,d ̆ ]. To prove our main and related results, we utilized some famous inequalities such as Gruss-inequality, Diaz-Mıtcaf’s inequality and Cauchy’s inequality. To prove our main results, we used a new multistep kernel (9-step linear kernel). Some related results are also discussed. In the end, we apply our results to numerical integration also.