#Region “AddComboboxColumn”
Public Sub AddComboboxColumn(ByVal headerText As String, _
ByVal datasource As Object, _
ByVal displayMember As String, _
ByVal valueMember As String, _
ByVal style As FlatStyle)
 
Dim cboc As New DataGridViewComboBoxColumn
cboc.HeaderText = headerText
cboc.DataSource = datasource
cboc.DataPropertyName = valueMember
cboc.DisplayMember = displayMember
cboc.ValueMember = valueMember
cboc.FlatStyle = style
 
Me._DataGridView.Columns.Add(cboc)
 
End Sub
#End Region

Dont forget to initialize the DataPropertyName or you wont see any data displayed in the datagridview combobox at runtime…