This has been asked before but none of other methods are working now.
Previously we were able to set Address Bar search or Search Bar to I'm Feeling Lucky, but Firefox has put a limit on those ways.
Is there any way now to add Google's I'm Feeling Lucky to Firefox's Search Bar or Address Bar?
I search a lot and 99% of the times I want the first result, while this might look being lazy for a click, I estimated that it is actually taking hours of my time monthly.
Best Answer
The URL for Google's "I'm Feeling Lucky" button is https://google.com/search?btnI=&q=%s (where %s is your search term).
The icon used is http://www.google.com/favicon.ico
Knowing these two, all you need to do is to construct your own OpenSearch XML plugin. Now you can do this manually of course, but there are sites that can do the work for you so why not use those?
One such site is Ready2Search. I already made the plugin for you. If you want to review or modify it just go here. To install the plugin in IE, Firefox or Chrome, just click the link that says "OpenSearch plug-in GoogleLucky" (to the right of the 3 browser icons). If you want to view the generated XML, click the "Download the setting of OpenSearch" button.
Enjoy!