On March 18, 2023, new underground platforms open at Osaka Station, allowing additional trains to stop at the station. The trains were formerly unable to serve Osaka Station due to the station's limited capacity.

Most notably, the Haruka airport trains, which formerly stopped only at Tennoji and Shin-Osaka, now also stop at Osaka. This results in shorter travel times between Kansai Airport and Osaka Station than before (about 20 minutes shorter compared to taking a direct airport rapid train). Travel on the Haruka limited express is fully covered by the Japan Rail Pass, and discounted one way tickets are also available for foreign travelers.

Also using the new underground tracks are the limited express trains bound for Wakayama, which make an additional stop at Osaka. Passengers will be able to travel directly to Wakayama from Osaka Station in less time than before. Additionally, the extension of the JR Osaka Higashi Line, which continues to Nara, also uses the new underground tracks.

The new underground platforms are located directly west of the current station building and connected by an underground passageway. One brand-new feature at the new platforms are the full-screen platform doors that display train information. These platform doors are said to be the first of their kind in the world. The line-up of futuristic technology also includes digital signage, which can display personalised directions when used in conjunction with the dedicated smartphone app.

The new underground platforms are located below the site of a large former rail yard north of Osaka Station, which is currently being redeveloped into a new, modern city district. Known as "Grand Green Osaka" the district will include generous park areas, residences, office space, shops and hotels. It is scheduled to start opening in 2025 and to be completed by spring 2028.