| Country: | TWN |
| Type: | PH |
| Route: | 9 |
| Map Custom: | yes |
| Length Km: | 453.851 |
| Direction A: | North |
| Terminus A: | in Zhongzheng District, Taipei |
| Junction: | in Toucheng, Yilan and Suao, Yilan |
| Direction B: | South |
| Terminus B: | in Fangshan, Pingtung |
| Previous Type: | PH |
| Previous Route: | 8 |
| Next Type: | PH |
| Next Route: | 10 |
Provincial Highway 9 is an important highway across eastern Taiwan from Taipei City to Fangshan, Pingtung, Pingtung County. This provincial highway, at 453.851 km long, is the second-longest provincial highway in Taiwan and passes the regions of Taipei City, New Taipei City, Yilan County, Hualien County, Taitung County and Pingtung County.[1]
The highway begins in front of the Executive Yuan in downtown Taipei. It continues along Zhongshan South Road (中山南路) and Roosevelt Road (羅斯福路) until it reaches Xindian, New Taipei. From there the highway follows Beixin Road (北新路) and later becomes Bei-Yi Highway (北宜公路). The highway passes through mountainous regions and enters Shiding and Pinglin in New Taipei City before reaching Yilan County.
In Yilan County, the highway finally leaves the mountainous region and enters the Yilan Plain, but not before a stretch of curvy mountain roads. The highway passes through Toucheng, Jiaoxi, Yilan City, Wujie, Luodong, and Dongshan before entering Su'ao. From Su'ao to Hualien, the highway is designated as Suhua Highway (蘇花公路), a set of curvy mountain roads known for its sharp curves and cliffs along the route. Suhua Highway passes through Su'ao and Nan'ao in Yilan County, Xiulin and Xincheng in Hualien County before entering Hualien City. In Xincheng the highway intersects the Central Cross-Island Highway, which provides access to Taroko National Park.
From Hualien City to Taitung City in Taitung County, the highway is known as the Huadong Highway (花東公路). The route serves as the primary north–south highway for the Huatung Valley townships. The highway connects the townships of Ji'an, Shoufeng, Fenglin, Guangfu, Ruisui, Yuli, and Fuli in Hualien County, as well as Chishang, Guanshan, Luye, Yanping, and Beinan, before reaching Taitung City.
From Taitung City, the highway is known as the South Link Highway. It continues south towards Taimali, where it meets Provincial Highway 11 and continues along the eastern coast of Taiwan. The highway then passes through Dawu and Daren. After its intersection with Provincial Highway 26 in Ansuo, a village in Daren, the highway turns westbound and cuts through the southern end of the Central Mountain Range, reaching Shouka. The highway continues to Shizi, Pingtung, and ends in Fangshan, Pingtung at the intersection of Provincial Highway 1.
In August 2015, the 9A branch line of the highway passing through Wulai District, New Taipei City was cut by landslides due to Typhoon Soudelor.[2]