Through a number of subsidiaries, it is engaged in various businesses, including manufacture of chemicals and petrochemicals, semiconductors, flash memory and miscellaneous information technology, as well providing telecommunications services worldwide among its other less notable ventures.

[2] While its largest businesses are primarily involved in the energy, petroleum, and chemical industries, the group also owns the nation's largest wireless mobile phone service provider SK Telecom, and provides services in construction, marketing, local telephone communications, high-speed internet, and wireless broadband WiBro.

[11][12] In 2002, SK Telecom successfully launched the world's first commercial CDMA 1X EV-DO technology, allowing it to offer 3G telecommunications service.

In May 2006, SK Telecom started the world's first commercial 3.5-generation HSDPA service, featuring high-quality video telephony and data transmission, and global roaming access.

[17] SK Gas began developing resources overseas when it participated in two mining areas to the west of Russia's Kamchatka peninsula in March 2006.

[18] SK Energy is currently engaged in 27 oil fields in 15 countries worldwide SKC imported propylene oxide (PO, a chemical used in manufacturing polyurethane) production technology from Germany in May 2006.

In February 2017, SK acquired the polyethylene acrylic acid business of Dow Chemical Company for $370 million,[25] and planned to increase battery production capacity from 1.9 to 3.9 GWh per year at the end of 2018, supplying Kia and Mercedes.

[26] In July 2022, SK Group announced a $22 billion investment in the United States semiconductor, green energy bioscience and other technology industries.

[27] SK Networks said August 20, 2024 it has sold its rental car unit for 820 billion won (US$618 million) to a Singapore-based private equity fund.