How to Install VirtualBox Guest Additions on CentOS 8

If you’ve ever run CentOS 8 as a virtual machine in VirtualBox, you know the default setup can feel clunky. Guest Additions fixes that. It gives you better screen resolution, shared clipboard, drag-and-drop support, and seamless folder sharing. Here’s how to get it installed without headaches.

💡 Related: How to Enlarge a Virtual Machine’s Disk in VirtualBox or VMware

Prerequisites

Before you start, make sure:

• CentOS 8 is up and running inside VirtualBox.
• You’re logged in as a user with sudo privileges.
• The VM has internet access.

Step 1: Update the System

First, bring everything up to date.

sudo dnf update -y
sudo dnf install -y epel-release

Then reboot:

sudo reboot

Step 2: Install Required Packages

Guest Additions needs kernel headers, development tools, and a few other packages.

sudo dnf install -y gcc kernel-devel kernel-headers make perl elfutils-libelf-devel

Check that the kernel version matches the installed headers:

uname -r
rpm -q kernel-devel

If they don’t match, run:

sudo dnf update -y
sudo reboot

Step 3: Mount the Guest Additions ISO

1. In the VirtualBox menu, go to Devices > Insert Guest Additions CD Image.
2. CentOS should auto-mount the disc. If not, do it manually:

sudo mount /dev/cdrom /mnt

Step 4: Run the Installer

Run the installation script from the mounted ISO:

sudo sh /mnt/VBoxLinuxAdditions.run

Watch for errors. If everything goes well, you’ll see messages saying modules were successfully installed.

Step 5: Reboot and Verify

After installation, reboot the VM:

sudo reboot

Now test:

• Resize the VM window – the desktop should resize with it.
• Try copy/paste between host and guest.
• Check shared folders (if configured).

Troubleshooting Tips

• Still stuck in 800×600? Check that your VirtualBox VM settings have Display > Graphics Controller set to VBoxSVGA.
• Errors during build? Make sure kernel-devel version matches the running kernel.
• No shared clipboard? Enable it under Devices > Shared Clipboard > Bidirectional.

Wrapping Up

Installing VirtualBox Guest Additions on CentOS 8 is a bit manual, but once done, your VM will feel a lot smoother and more integrated. If you run into issues, check logs in /var/log/VBoxGuestAdditions.log for clues.

Have a bloated or undersized virtual disk? Check out this quick guide: How to Enlarge a Virtual Machine’s Disk in VirtualBox or VMware

Let me know in the comments if you hit any snags or need help with a specific error.