Wakashio services operate over the Keiyo Line and Sotobo Line, stopping at the following stations. Some services terminate at Kazusa-Ichinomiya, and some services operate as "Local" all-stations services between Katsuura and Awa-Kamogawa.
The Wakashio service commenced on 15 July 1972, using 183 series EMUs. Evening Hometown Wakashio services for commuters were introduced from 16 March 1991, operating from Tokyo to Kazusa-Ichinomiya. New 255 series EMUs were introduced from 2 July 1993, initially branded as View Wakashio. Morning Oyaho Wakashio services for commuters were introduced from 3 December 1994, operating from Kazusa-Ichinomiya to Tokyo. New E257-500 series EMUs were introduced from 16 October 2004, displacing the remaining 183 series trainsets. From the start of the revised timetable on 10 December 2005, Wakashio services were made entirely no-smoking.
The opening of the Tokyo Bay Aqua-Line road across the Tokyo Bay in 1997 saw increased competition from long-distance bus services offering cheaper fares, resulting in decreasing ridership figures on the Wakashio services. From the start of the 15 March 2014 timetable revision, the number of services was reduced from 15 to 13 return workings daily.