How to detect DataGridView CheckBox event change?

To handle the DatGridViews CheckedChanged event you must first get the CellContentClick to fire (which does not have the CheckBoxes current state!) then call CommitEdit. This will in turn fire the CellValueChanged event which you can use to do your work. This is an oversight by Microsoft. Do some thing like the following...

private void dataGridViewSites_CellContentClick(object sender, 
    DataGridViewCellEventArgs e)
{
    dataGridViewSites.CommitEdit(DataGridViewDataErrorContexts.Commit);
}

/// <summary>
/// Works with the above.
/// </summary>
private void dataGridViewSites_CellValueChanged(object sender, 
    DataGridViewCellEventArgs e)
{
    UpdateDataGridViewSite();
}

I hope this helps.

P.S. Check this article https://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.currentcelldirtystatechanged(v=vs.110).aspx

I found @Killercam's solution to work but was a bit dodgy if the user double clicked too fast. Not sure if other's found that the case either. I found a another solution here.

It uses the datagrid's CellValueChanged and CellMouseUp. Changhong explains that

"The reason for that is OnCellvalueChanged event won’t fire until the DataGridView thinks you have completed editing. This makes senses for a TextBox Column, as OnCellvalueChanged wouldn’t [bother] to fire for each key strike, but it doesn’t [make sense] for a CheckBox."

Here it is in action from his example:

private void myDataGrid_OnCellValueChanged(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)
    {
        // Handle checkbox state change here
    }
}

And the code to tell the checkbox it is done editing when it is clicked, instead of waiting till the user leaves the field:

private void myDataGrid_OnCellMouseUp(object sender,DataGridViewCellMouseEventArgs e)
{
    // End of edition on each click on column of checkbox
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)
    {
        myDataGrid.EndEdit();
    }
}

Edit: A DoubleClick event is treated separate from a MouseUp event. If a DoubleClick event is detected, the application will ignore the first MouseUp event entirely. This logic needs to be added to the CellDoubleClick event in addition to the MouseUp event:

private void myDataGrid_OnCellDoubleClick(object sender,DataGridViewCellEventArgs e)
{
    // End of edition on each click on column of checkbox
    if (e.ColumnIndex == myCheckBoxColumn.Index && e.RowIndex != -1)
    {
        myDataGrid.EndEdit();
    }
}

jsturtevants's solution worked great. However, I opted to do the processing in the EndEdit event. I prefer this approach (in my application) because, unlike the CellValueChanged event, the EndEdit event does not fire while you are populating the grid.

Here is my code (part of which is stolen from jsturtevant:

private void gridCategories_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == gridCategories.Columns["AddCategory"].Index)
    {
        //do some stuff
    }
}



private void gridCategories_CellMouseUp(object sender, DataGridViewCellMouseEventArgs e)
{
    if (e.ColumnIndex == gridCategories.Columns["AddCategory"].Index)
    {
        gridCategories.EndEdit();
    }
}