Recently, scholars and practitioners have shown an increased interest in the field of sustainable supplier selection and order lot-sizing. While several studies have recently been carried out on this field, far too little attention has been given to formulating a multi-objective model for the integrated problem of multi-period multi-product order lot-sizing and sustainable supplier selection under inflationary conditions. In this study, a mathematical model for multi-period multi-product lot-sizing and sustainable supplier selection under the effects of inflation is developed. The proposed model includes four objective functions which minimize total cost and maximize total social, total environmental, and total economic qualitative scores. The model attempts to simultaneously balance different costs under inflationary conditions to optimize the total cost of purchasing and other objective functions. The applicability of the proposed model is shown by an illustrative example. The results show that the proposed model can provide an effective purchasing plan for the company while monitoring the effect of inflation and assuaging its concerns regarding sustainability issues.