Upgraded version for the power user of Rename/Merge Categories plugin by Macedonian WP Team.
Use this plugin to rename and merge multiple existing categories. The difference is that it uses checkboxes and radio buttons instead of an inneficient dropdown list. Also, the “Delete first category” option is now checked by default.
Here’s a screenshot : 
Works with WordPress 2.5+
Download Bulk Rename/Merge Categories WordPress Plugin
Comments are welcome. Good luck!
Hey, thanks for the great plugin. I do have one suggestion though, if you changed the ‘delete first category’ to a ‘delete unused category’ function, it would be a perfect plugin – because if you are merging to the first category, you can’t delete it, you have to go back and manually delete it. Just a thought – it’s a great plugin and a life saver as it is!
Comment by Jason Block — December 4, 2008 @ 12:57 pm
Hi. Any chance that this can be tweaked to work with 2.7? Its a really good solution but at the minute, only the renaming part works with 2.7 and the merge does not seem to do anything.
Comment by abi davis — January 7, 2009 @ 7:40 am
I was able to install & activate this plugin, but it doesn’t work for me. I can rename, but I cannot merge. When I try to merge, it doesn’t give me an error, but the page just refreshes
I’m using WP 2.7, and I noticed my plugin page looks different than your screenshot. Click here to see my screenshot.
Any ideas?
Comment by Matt Jabs — January 8, 2009 @ 4:40 am
Hi
A very useful plugin but the merge option doesn’t work for me on 2.8.5. More details on http://wordpress.org/support/topic/231870
Hope you can solve it, because the plugin is very important.
Best wishes
Gury
Comment by Gury — October 29, 2009 @ 7:46 am
[...] to backup your database before making any changes! Alternatively this plugin also does the job.. WordPress Category Merge [...]
Pingback by Merging Categories in Wordpress | ViperPilot — April 1, 2010 @ 10:42 am
I am a bit confused. So this plugin is for webmasters who have a website and have already created categories for their wordpress blog AND NOW want to change their site archetecture my renaming/deleting or otherwise changing the content siloes?
Your thoughts? Please let me know if this is correct. If so, this plug-in sounds like it would nice solve some SEO challenges as well as aiding the webmaster’s job!
Comment by Dannyboy — August 13, 2010 @ 6:54 pm