In 1978, Loh founded the Cooma, Lau & Loh legal team and became Managing Partner. He was appointed Senior Counsel in 1999. He moved to the Executive Committee of Rajah & Tann in 2001, and became Deputy Managing Partner in 2003. He also served as Director of a dispute resolution complex until 2009.
Loh was first appointed to the Supreme Court of Singapore as a Judicial Commissioner on 1 September 2009. On 1 June 2010, he was elevated to the position of High Court Judge. In December 2017, his term was extended by three years by president Halimah Yacob, and he was sworn in on 4 January 2018. He has occasionally sat on the Court of Appeal of Singapore during periods with a high caseload.
Loh is in charge of the Singapore International Commercial Court (SICC), and chairs both the SICC Development Committee and the SICC Rules Committee. He also chairs the Personal Injury (Claims Assessment) Review Committee and the Professional Training of Lawyers group. During the SICC’s first case in November 2015, he said:
This court signifies not only the aspirations of Singapore to establish itself as a dispute-resolution hub, but it also reflects the needs of international trade and commerce… for different kinds of dispute-resolution methodologies.
As a judge, he specialises in law relating to construction, commercial litigation, and domestic and international arbitration.