Yes, with the start command. Example:

start http://www.google.com

That will use the user's default browser.
As stated by Joey, you should use a different format for URLs with special chars:

start "" "http://www.google.com"

& is a special character in bash, so if the URL contains a special character you just have to do it like this:

start "" "your url" 

Windows

explorer "https://google.com"

Which will launch your default browser and navigate to that site.

As @RiverHeart pointed out if your URL has special characters like ? you can escape the URL like so in Windows 10+

explorer "`"https://www.google.com/search?q=hello+there"`"

MacOS

open "https://google.com"

You can do it like:

firefox -new-tab "https://www.useotools.com"

OR with full path

"C:\Program Files\Mozilla Firefox\firefox.exe" -new-tab "https://www.useotools.com"

You know how sometimes the answer to the question you ask is not necessarily the answer you need? I have a vague suspicion this might be one of those times.

If this is a Windows machine you're trying to reboot, you can reboot it remotely without needing to use a CGI script served by the remote host. If the account you're logged in with on the triggering PC also has privileges on the remote PC, you can trigger the reboot with the shutdown command.

shutdown /m \\remotePC /r /t 0

Do shutdown /? in a cmd console for more info. Or if you must authenticate, you can use wmic instead.

wmic /node:remotePC /user:remotePCadmin /password:remotePCpass process call create "shutdown -r -t 0"

In case I was mistaken, here's the answer to the question you asked. The fastest way to execute a remote CGI script would be to use an XMLHTTPRequest with Windows Script Host (VBScript or JScript). Here's an example.

@if (@CodeSection == @Batch) @then
@echo off & setlocal

set "URL=http://192.168.1.100/cgi-bin/reboot"
cscript /nologo /e:jscript "%~f0" "%URL%"

goto :EOF
@end // end batch / begin JScript chimera

var x = WSH.CreateObject("Microsoft.XMLHTTP");

x.open("GET",WSH.Arguments(0),true);
x.setRequestHeader('User-Agent','XMLHTTP/1.0');
x.send('');
while (x.readyState != 4) WSH.Sleep(50);

For what it's worth, you can also parse x.responseText as needed. You can scrape it as flat text, or even evaluate it as a hierarchical DOM object. This answer demonstrates such parsing. And if you just can't get enough, here are more examples.

If you'd rather have something simpler at the expense of efficiency, you can invoke a PowerShell command.

@echo off & setlocal

set "URL=http://192.168.1.100/cgi-bin/reboot"
powershell "ipmo BitsTransfer; Start-BitsTransfer \"%URL%\" \"%temp%\a\""
del /q "%temp%\a"

goto :EOF

You could probably alternatively use Invoke-WebRequest to avoid the temporary file, but Invoke-WebRequest requires PowerShell version 3 or newer. Start-BitsTransfer works with PowerShell version 2, so it should work on more computers. One might also use the [System.Net]::WebRequest .NET class, but it gets a little complicated constructing all the objects needed to proceed beyond fetching the HTTP headers to having the web server serve the web page. If you're curious, it looks something like this:

powershell "void.GetResponse().GetResponseStream())).ReadToEnd()"

Not exactly what I'd call simple. In hybrid format for easier readability:

<# : batch portion
@echo off & setlocal

set "URL=http://192.168.1.100/cgi-bin/reboot"
powershell -noprofile "iex (${%~f0} | out-string)"

goto :EOF

: end batch / begin PowerShell hybrid chimera #>

$request = [Net.WebRequest]::Create($env:URL)
$response = $request.GetResponse()
$stream = $response.GetResponseStream()
$reader = new-object IO.StreamReader($stream)
[void]$reader.ReadToEnd()

In any case, any PowerShell solution will be a second or two slower than the JScript solution near the top of this answer. powershell.exe takes a second or two to load (indeed, several seconds if it's not been loaded since Windows was last rebooted); whereas cscript.exe fires nearly instantly.