The PlayStation Portable system software is the official firmware for the PlayStation Portable (PSP). It uses the XrossMediaBar (XMB) as its user interface, similar to the PlayStation 3 console.

Updates add new functionality as well as security patches to prevent unsigned code from being executed on the system. Updates can be obtained in four ways:

While system software updates can be used with consoles from any region, Sony recommends only downloading system software updates released for the region corresponding to the system's place of purchase. System software updates have added various features including a web browser, Adobe Flash Player 6 support, additional codecs for images, audio, and video, PlayStation 3 connectivity, as well as patches against several security exploits, vulnerabilities, and execution of homebrew programs. The battery must be at least 50% charged or else the system will prevent the update from installing. If the power supply is lost while writing to the system software, the console will no longer be able to operate unless the system is booted in service mode or sent to Sony for repair if still under warranty.

The current version of the software, 6.61, was made available on January 15, 2015. It is a minor update released more than three years after the release of the previous version 6.60 in 2011.

The PlayStation Portable uses the XrossMediaBar (XMB) as its graphical user interface, which is also used in the PlayStation 3 (PS3) console, a variety of Sony BRAVIA HDTVs, Blu-ray disc players and many more Sony products. XMB displays icons horizontally across the screen that be seen as categories. Users can navigate through them using the left and right buttons of the D-pad, which move the icons forward or back across the screen, highlighting just one at a time, as opposed to using any kind of pointer to select an option. When one category is selected, there are usually more specific options then available to select that are spread vertically above and below the selected icon. Users may navigate among these options by using the up and down buttons of the D-pad.

The basic features offered by XMB implementations varies based on device and software version. On the PSP console, the XMB had top level icons for Photos, Music, Videos, Games, Networking (which allows the use of the web browser), Settings and Extras. Also, XMB offers a degree of multitasking. With the PSP, using the Home button while playing music would allow users to browse photos without stopping the music. While XMB proved to be a successful user interface for Sony products such as PSP and PS3, the next generation Sony video game consoles such as the PlayStation 4 and the PlayStation Vita no longer use this user interface. For example, the XMB is replaced by the LiveArea interface on the PS Vita.

The PlayStation Portable comes with a web browser for browsing the Internet. The web browser is a version of the NetFront browser made by Access Co. Ltd. and was released for free with the 2.00 system software update. The browser supports most common web technologies, such as HTTP cookies, forms, CSS, as well as basic JavaScript capabilities.

The version 2.50 upgrade added Unicode (UTF-8) character encoding and Auto-Select as options in the browser's encoding menu, and also introduced the saving of input history for online forms.