In this short code snippet article, I have explained how to automatically scroll then ASP.Net Multiline TextBox to Bottom using JavaScript on Page Load.
To explain its working I have made use of another ASP.Net TextBox with a Button that will be used to add text dynamically to the multiline TextBox
<asp:TextBox ID="TextBox1" runat="server" Text="Sample Text"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Add" OnClick="Button1_Click" />
<hr />
<asp:TextBox ID="TextBox2" runat="server" TextMode="MultiLine" Height="100"></asp:TextBox>
<script type="text/javascript">
    window.onload = function () {
        var textarea = document.getElementById('<%=TextBox2.ClientID %>');
        textarea.scrollTop = textarea.scrollHeight;
The following code is executed to button click event
protected void Button1_Click(object sender, EventArgs e)
    TextBox2.Text += TextBox1.Text + "\n";
In order to scroll the Multiline TextBox to bottom, I have executed some JavaScript code on the window onload event of the page. First I have access the Multiline TextBox and then I am setting its scroll position to that of its scroll height, which makes the scroll bar of the Multiline TextBox scroll to the bottom