Style.HorizontalAlignment (Excel)

Returns or sets an XlHAlign value that represents the horizontal alignment for the specified object.

xlHAlignCenter - Center, xlHAlignCenterAcrossSelection - Center across selection, xlHAlignDistributed - Distribute, xlHAlignFill - Fill, xlHAlignGeneral - Align according to data type, xlHAlignJustify - Justify, xlHAlignLeft - Left, xlHAlignRight - Right.

Some of these constants may not be available to you, depending on the language support (U.S. English, for example) that you've selected or installed.

ActiveCell.Style.HorizontalAlignment = xlHAlignCenter
Style.HorizontalAlignment procedure builder