I Squared Capital was founded in 2012 by former senior executives at Morgan Stanley, including Sadek Wahba, Adil Rahmathulla, and Gautam Bhandari.

In August 2015, the firm invested US$150 million into Amplus Energy Solutions Private Limited, an Indian rooftop solar power company.

[13] In December 2015, I Squared purchased the 220 mi (350 km) pipeline gathering system owned by WPX Energy in the San Juan Basin in New Mexico.

[14] In January 2016, I Squared acquired Lincoln Clean Energy which develops and operates wind farms across North America, including two in Texas.

[17] In October 2016, I Squared Capital agreed to acquire Duke Energy's hydroelectric and natural gas business in Peru, Chile, Ecuador, Guatemala, El Salvador, and Argentina for US$1.2 billion.

[21] The acquisition included the submarine fiber network, data center infrastructure and services of GTT Communications in Europe and North America.

[28] In January 2024, I Squared bought 49% of Órigo Energia, a Brazilian renewable energy company which builds and operates solar farms near cities.