How to Install a Theme in OpenCart 3.x

Posted by Will Wakeford on December 9, 2025

OpenCart themes enhance the look and feel of your e-commerce website, allowing you to create an identity which matches your brand and style. Installing a theme is relatively straightforward - this article will provide everything you need to know to get one installed and set up on your site.

1. Choosing a Theme

The first, and possibly most important, step is selecting the right theme for your store. There are plenty to choose from on the OpenCart Marketplace, and it's important to choose one that's right for you. We highly recommend looking out for the following things, to ensure you find a well-built and robust theme:

• Use a CSS-only theme. This means that the theme does not override any of the core OpenCart files, keeping the styling separate. A theme that rewrites core files is very likely to cause problems down the line, like breaking extensions or any future updates. A theme that only consists of CSS is also extremely lightweight, keeping your website as fast as possible and improving SEO.
• Compatibility. Make sure that the theme extension files are compatible with your version of OpenCart.
• Responsiveness. You'll want to make sure your chosen theme looks good across all devices, especially desktop and mobile. You don't want to go through the effort of finding and installing an extension, just for your store to look even worse on mobile! If possible through demos or images, check how the theme will look on mobile devices.

We have a brilliant selection of CSS-only themes, make sure to have a browse and test them out here: https://themes.antropy.co.uk/

2. Downloading/Installing the Theme

Once you have found your chosen theme and made sure your OpenCart version is listed under Compatibility, download the theme files. Once downloaded, you should have an upload folder, along with an install.xml file enclosed in a compressed file ending in the format [theme].ocmod.zip.

The next step is to upload the theme to Opencart, which is made nice and easy with the extension installer in OpenCart 3. Go to Extensions -> Installer and upload the zipped OCMOD file. You should receive a success message.

3. Enabling the Theme

Now the theme has been installed, the next step is to enable the theme.

1. Make sure to refresh the modification cache in Extensions -> Modifications.
2. In the OpenCart Admin go to Extensions -> Extensions -> Themes and click the install button on the new theme. Click edit and change the status to enabled, ensuring the Theme Directory is correct.
3. Go to System -> Settings, click edit and change the theme to the one you've just installed.

Open your website homepage, and just like that, the theme has been applied!