How to use Microsoft office EXCEL CONCATENATE function easily and efficiently This function in excel is used to connect cells values into one value. What is Excel concatenation function? The Microsoft Excel CONCAT function allows you to join 2 or more strings together. It was released in Excel 2016 and replaces the CONCATENATE function. The CONCAT function is a built-in function in Excel that is categorized as a String/Text Function. It can be used as a worksheet function (WS) in Excel. As a worksheet function, the CONCAT function can be entered as part of a formula in a cell of a worksheet.