The Kyushu Shinkansen (九州新幹線, Kyūshū Shinkansen) is a Japanese Shinkansen high-speed railway network. It is an extension of the San'yō Shinkansen from Honshu connecting the city of Fukuoka (Hakata Station) in the north of Japan's Kyushu Island to the city of Kagoshima (Kagoshima-Chuo Station) in the south. The line runs parallel to the existing Kagoshima Main Line and is operated by Kyushu Railway Company (JR Kyushu).

The southernmost 127 km (79 mi) section of the track was constructed first, opening on 13 March 2004. The dual-track offered a significant improvement in transit time over the equivalent single-track section of the Kagoshima Main Line, despite the need for passengers to change to a Relay Tsubame narrow gauge train at Shin-Yatsushiro, and the remainder of the journey to Hakata Station. The northernmost 130 km (81 mi) section opened on 12 March 2011, enabling through-services to Shin-Osaka (and with an interchange, to Tokyo). However, opening ceremonies were cancelled due to the 2011 Tōhoku earthquake and tsunami.

The Nishi Kyushu Shinkansen route to Nagasaki (from Takeo-Onsen to Nagasaki) opened on 23 September 2022. A cross-platform interchange to a relay service called 'Relay Kamome' at Takeo-Onsen station offers a connection to Hakata.

Construction of the Kagoshima route (鹿児島ルート) began in 1991, and the first segment between Kagoshima and Shin-Yatsushiro opened on 13 March 2004. This initial section cut travel times between the two cities from 2 hours and 10 minutes to 35 minutes and reduced the time between Hakata and Kagoshima from 4 hours to 2 hours. When the entire line was completed, the travel time from Hakata to Kagoshima was further reduced to about an hour and 20 minutes. As of 2012, the maximum line speed is 260 km/h (160 mph) between Hakata and Kagoshima. Like all Shinkansen lines, the Kyushu Shinkansen is standard gauge.^{[citation needed]}

The line's Sakura and Mizuho services often operate through to Shin-Ōsaka Station via the San'yō Shinkansen. All-stop trains are named Tsubame ("Swallow"), the name of the former Hakata-Kagoshima limited express service, and are solely truncated to the Kyushu Shinkansen.

In September 2011, six months after the line's completion, JR Kyushu reported a year-over-year increase in ridership of 64% to the southern part of Kyushu (between Kumamoto and Kagoshima), easily surpassing the 40% increase projected by the company. By the first anniversary, ridership had increased, mainly from tourists from Kansai and Chugoku. In northern Kyushu, where there is fierce competition with conventional JR rapid service, the private Nishi-Nippon Railroad, and expressway buses, Shinkansen ridership increased by only 38% (compared to the now-discontinued conventional express Relay Tsubame), falling short of estimates.

A Shinkansen line from Fukuoka to Nagasaki, initially known as the Nagasaki Shinkansen (長崎新幹線), was laid out in the 1973 Basic Plan. Renamed as the Nagasaki Route (長崎ルート), then changed to the Nishi Kyushu Route (西九州ルート, Nishi Kyūshū rūto) in 1995, the segment between Takeo-Onsen and Nagasaki, Nishi Kyushu Shinkansen, opened for service on 23 September 2022.

According to the Shinkansen Basic Plan laid out in 1973, two other routes would accompany the Kagoshima and West Kyushu (Nagasaki) routes: the East Kyushu Shinkansen, from Hakata to Kagoshima-Chūō via Ōita and Miyazaki, paralleling the Nippō Main Line; and the Trans-Kyushu Shinkansen, linking Kumamoto and Ōita, and connecting with the also-planned Shikoku Shinkansen to Matsuyama, Takamatsu and Osaka. These plans have been shelved indefinitely and are unlikely to be reconsidered until the Shinkansen lines that are already under construction are completed.