Appointed as Siam Premier’s Managing Partner on 1 October 2020, Chatchavej is a Partner with over 25 years’ experience in advising multinational corporations (including many corporations listed in Fortune Global 500), large Thai corporations, and Thai government agencies on corporate / M&A, antitrust and competition, real property and construction, insurance, PPPs, regulatory matters, government contracts, and all aspects of foreign investment in Thailand. He regularly acts on global acquisitions dealing with Thai assets across a broad range of sectors including automotive, energy, property, insurance, pharmaceutical, hospitality, manufacturing e-commerce and retail, where he works closely with clients, their advisors, and international counsel from global law firms.

Recently, Chatchavej has ranked in Corporate/M&A, Insurance and Real Estate by Chambers Asia-Pacific (2026), recognized as “Leading Lawyer” in Real Estate and Construction by Legal 500 Asia (2025), recognized as “Highly Regarded” lawyer in M&A by IFLR1000 (2025), ranked in A-List Thailand's Top Lawyers 2025 by Asia Business Law Journal, and named as a Distinguished Practitioner (Corporate/M&A) in Asialaw Leading Lawyers (2025).

In 2026 Guide, Chambers Asia-Pacific provided the quotes about his works:    "What sets him apart is his ability to spot potential risks others may not see, offering proactive solutions to help avoid future complications." and "We are very impressed by Chatchavej Chitvarakorn's services. He is able to provide out-of-the-box solutions, which we are very happy about."

In addition to his role as Partner, Chatchavej is co-lecturer in the Relationship between Business and Law course in the Master in Arts in Economic Law program in the Faculty of Law at Chulalongkorn University. He also serves as a board member of the Chevening Alumni Association of Thailand under the Foreign Commonwealth Office through the British Embassy in Thailand. Chatchavej is a director of Siam Premier International Law Office Limited and an independent director of Vara Food and Drink Co., Ltd.

• Acting for a UK headquartered global health insurance company on the THB 2.17 billion sale of its Thai subsidiary to a US managed global health insurance company.
• Acting for a Swiss-based global pharmaceutical company on the USD 5.4 billion disposal of its animal health business to a US global animal health company with respect to Thai assets.
• Acting for a global life insurance company and its Thai subsidiary in the THB 17.5 billion 100% share acquisition of a life insurance subsidiary of a SET-listed bank.
• Acting for a Spanish headquartered global energy company on its USD 2.23 billion acquisition of an international exploration and production company with respect to Thai assets.
• Advising a foreign EPC contractor on the RFP, Project Agreement and Thai legal environment in the bidding phase of the THB 220 billion High Speed Rail Linking Three Airports PPP Project. 
• Representing a Japanese infrastructure company on its acquisition of a biomass power plant in Thailand.
• Advising numerous leading global hotel brands on share and asset acquisition and hotel management in respect of property in Thailand.
• Advising one of the largest SET-listed property and hotel developers and operators in multiple transactions in relation to share acquisitions in a number of joint ventures.

LL.B. Chulalongkorn University (First Class Honors)
LL.M. The London School of Economics and Political Science (Merit) on the British Chevening Scholarship
Barrister-at-law