Kharel joined UML in 2036 BS after taking membership of the party. He became secretary of the student wing of the party at MahendraBideshwari Multiple Campus in 2036 BS. He was elected central member of the Nepal Bar Association in 2045 BS.
He worked as the legal advisor to Madhav Kumar Nepal who was a member of the constitution drafting committee in 2047 BS.
The party assigned him the role of general convention representative and member of the election committee during the party's general convention in 2049 BS.
He was nominated member of UML's national council in 2050 along with Subash Nembang, Bidya Bhandari, Bharat Pradhan and BishnuRimal. Kharel was elected central committee member through the eighth national convention held in 2066 BS. He became a politburo member through the ninth general convention and was elected standing committee member through the tenth general convention of the party.
Kharel became a Constituent Assembly member in 2065 through the proportional representational system and worked as a member of the Constitution Drafting Committee in 2066 BS. He was nominated as an expert in the second Constituent Assembly.
He served as Minister for Law in 2072 BS and Attorney General in 2076 BS.