Line 9 is a southwest-northeast line of the Shanghai Metro network. The line runs from Shanghai Songjiang Railway Station in Songjiang District to Caolu in Pudong. The line is colored light blue on system maps.

In the initial planning of Line 9, the entire line was from Fengjing to Chongming Island. Later, the plan to extend to Fengjing was cancelled, and the section to Chongming Island was changed to Chongming line.

The first phase of Line 9, from Songjiang Xincheng to Guilin Road stations, opened on December 29, 2007. It uses the Bombardier Movia trains which were lent to line 1.

Line 9 did not directly connect to the rest of the Shanghai Metro network until the opening of the Line 9 portion of the Yishan Road station on December 28, 2008. The station is an interchange between lines 3 and 4. A shuttle bus conveyed passengers between Guilin Road and Yishan Road stations until construction was completed.

In December 2009, the second phase of line 9 (from Yishan Road to Century Avenue) was completed, providing passengers with a direct link from Songjiang District in the west to Pudong in the east without having to transfer to other lines.

On April 7, 2010, the extension to Middle Yanggao Road Station was completed.

On December 30, 2012, the extension from Songjiang New City to Songjiang South Railway Station was opened.

On December 30, 2017, the line's east extension, consisting of nine stations from Middle Yanggao Road to Caolu, entered operation.