Joshua joined the firm upon his graduation from the University of Singapore in 1979 and was admitted to the Singapore bar in 1980. In early 1984, he was admitted as a partner, making it to equity partnership in 1986.
In 1992, Joshua left Lee & Lee and joined the Singapore Legal Service where he served as a District Judge with the Subordinate Courts for 2 years and thereafter, as a Senior State Counsel with the Attorney-General's Chambers where he held the appointment of Deputy Head, Civil Division. In 2000, he rejoined Lee & Lee as a Partner.
Joshua holds various directorships in civic and corporate organizations. He also sits as a member of the Military Court of Appeal. Joshua has enjoyed a versatile litigation practice that spans both civil and criminal matters at trial as well as appellate levels.