Corrosion damage has been identified as the most degrading mechanism in steel structure especially in offshore topside plated structure. Meanwhile, blast load is an extreme loading condition prevail in an offshore environment that able to generate severe impact to offshore topside structure. Though statistics shows that accidental explosion events only occur at low frequency, but the damage involve major fatalities to personnel, asset and environment. Blast load response of corroded offshore plated topside structure has not been well studied. Therefore, in this work, parametric study is carried out on a corroded offshore structural plate. Degree of pitting (DOP) is the influenced parameter, used variably on a plate to study the response subjected to blast load. Finite element analysis (FEA) is used where simulation is done based on the influence parameter. Deflection of plate increases with increasing DOP. Interestingly, plate with DOP of 0.35�12.6 has lower deflection as compared to non-corroded plate when subjected to blast loads. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.