Hawaiian Electric Industries, Inc. (HEI; NYSE: HE) is the largest supplier of electricity in the state of Hawaii, supplying power to 95% of Hawaii's population through its electric utilities: Hawaiian Electric Company, Inc., Hawai'i Electric Light Company, Inc. and Maui Electric Company, Limited. In addition, HEI owns a financial institution serving Hawaii, American Savings Bank. (The island of Kauai is the only island in the state not supplied by HEI. Instead, the consumer-owned Kauai Island Utility Cooperative manages the island's electricity.)

HECO, HELCO, and MECO employ more than 2,000 people. Approximately 20,000 Hawaii residents are shareholders of HECO’s parent company, Hawaiian Electric Industries (HEI). The company is headquartered in Honolulu. The net income of the company reached 164 million dollars by the end of 2012 with a yearly revenue of 3.4 billion dollars.

Hawaiian Electric Company (often abbreviated HECO, pronounced HEE-coh) incorporated on October 13, 1891. Within about 16 years the utility had 2,500 customers on the island of Oahu. By 1914 HECO had started rural service to the windward side of the island and was marketing electric products like refrigerators and flat irons. By 1937 HECO broke ground on its second power plant, and transmission lines soon crisscrossed Oahu.

During World War II HECO power plants, now linked to busy military bases, generated more than one million kilowatt hours of electricity each day.

Hawaii became a state in 1959, and by then the entire island of Oahu was electrified. Massive power plants, some still in operation today, came online. HECO flipped the switch on a 116 MW plant in downtown Honolulu in 1954. The state's first reheat steam turbine generator went on line at Kahe on the west coast of Oahu. Today, Kahe is the state's largest plant with a total generating capacity of 650 MW.

HECO purchased Maui Electric Company (abbreviated MECO and pronounced ME-coh) in 1968. In 1970 HECO also acquired the Big Island's Hilo Electric Light Company (later to be renamed Hawaii Electric Light Company, abbreviated HELCO and pronounced HEL-coh). MECO had expansion plans of its own. In 1988, it acquired the Lanai City power plant on the island of Lanai, and in 1989, Molokai Electric Company on the island of Molokai. Hawaiian Electric Industries, Inc. (HEI) was created as a holding company for these various utilities in 1983. At the moment, HECO is developing a self-healing grid in eastern Oahu and Waikiki, to ensure a reliable electrical supply.

On December 4, 2014, NextEra Energy tendered an offer to purchase HEI for $4.3 billion. The sale required approval by the Hawaii Public Utility Commission. On July 18, 2016, it was announced that the merger was cancelled after the State PUC disapproved the deal. The merger included plans to convert HEI's oil-fired generating plants to run on natural gas, which were to use liquified natural gas imported from a British Columbia plant of FortisBC. The upgrades were cancelled as they were dependent upon approval of the merger.

In 2016 HECO produced 8.8 TWh, of which 2.3 TWh were renewable. Most of the power came from oil, using 8.5 million barrels in 2016, down from 10.7 million barrels in 2008.

Oahu: total firm generating capability in 2016 was 1,726.5 megawatts for 304,261 customers, with 19.4% coming from renewable resources.

Maui: total firm generating capability is 274.1 megawatts for 70,872 customers, with 36.9% coming from renewable resources.

Big Island: total firm generating capability 281.4 megawatts for 85,029 customers, with 54.2% coming from renewable resources.

Through a cooperative effort with HECO, High Technology Development Corporation (HTDC), an agency of the State of Hawai’i, initiated the Hawai’i Electric Vehicle Demonstration Project (HEVDP) consortium to develop an electric vehicle industry in Hawai’i. The islands have about 5,000 rechargeable vehicles.

In 2015, the Hawaii State Legislature amended the State's Renewable Portfolio Standards to establish the nation's first goal of 100% renewable energy:

Hawaiian Electric has indicated in its Power Supply Improvement Plan that it will achieve these goals early, including achieving 100% renewable electricity for the island of Moloka'i by the year 2020.