Christiani & Nielsen was founded in Denmark by Dr. Rudolf Christiani, a young civil engineer, and Captain Aage Nielsen, an officer in the Royal Danish Navy. The initial aim of the company was to use its technical and design expertise to develop the use of reinforced concrete, particularly for bridges and marine works.

As its reputation for engineering excellence grew, Christiani & Nielsen expanded internationally, establishing operations in Germany (1908), the United Kingdom (1913), South America (1919), Thailand (1930), and South Africa (1938), with further expansion into many other countries in the years that followed.

Christiani & Nielsen (Siam) Ltd. was established in Thailand with its principal shareholders comprising H.M.'s Privy Purse (now the Crown Property Bureau), The East Asiatic Company Limited, and Christiani & Nielsen A/S of Copenhagen, Denmark. This marked the beginning of a long-standing presence in the Kingdom and laid the foundation for the Company's significant contribution to Thailand's infrastructure development over the decades.

Many of the Company's early projects became important milestones in Thailand's development, including Tripetch Road (1931), Bangkok's first concrete road; the Democracy Monument (1940); Khlong Toei Port (1941); and the 10-storey extension of The Oriental Hotel (1958), recognized as Thailand's first reinforced concrete high-rise building.

Christiani & Nielsen (Thai) Ltd. became the first construction company listed on the Stock Exchange of Thailand. In 1992, the company was renamed Christiani & Nielsen (Thai) Public Company Limited, and completed a reverse takeover of its publicly listed Danish parent company, the first such transaction in Thai history.

The Crown Property Bureau sold its shares to Globex Corporation, part of the GP Group with a long history in Thailand dating back to 1918. Globex became the major shareholder of the Company.

To capitalize on the growing opportunities in the solar and renewable energy sectors, the Company established Christiani & Nielsen Energy Solutions Co., Ltd. (CNES). This strategic expansion diversified the Company's business portfolio while helping to mitigate risks associated with increasing competition in the construction industry. Subsequently, CNES established CNES D1 Co., Ltd. to develop and operate renewable energy power generation projects, supporting the Group's long-term commitment to sustainable growth and clean energy development.

The Company established Christiani & Nielsen DCM Co., Ltd. to expand into the hospitality and leisure sector, creating new revenue streams and supporting long-term sustainable growth.

The Company established CN Property Co., Ltd. to pursue opportunities in real estate development throughout Thailand, expanding its capabilities across a broad range of property and construction-related projects.