[6] He was later named by fellow senatorial candidate Robin Padilla as his legislative adviser and mentor in the Senate.

[11][2][3] Panelo started practiced law at United Laboratories where he served as the company's legal counsel from 1977 to 1987.

[12] In his 40 years of law practice, he served as the defense lawyer of prominent politicians such as Datu Unsay Mayor Andal Ampatuan Jr. who was implicated in the 2009 Maguindanao massacre, Calauan Mayor Antonio Sanchez who was tried for the 1993 Eileen Sarmenta and Allan Gomez murder, and the family of former President Ferdinand Marcos in relation to recovering their ill-gotten wealth.

His other clients include celebrities such as Deniece Cornejo in her 2014 rape case against actor Vhong Navarro, and Dennis Roldan who was convicted of kidnapping a Filipino-Chinese boy in 2005.

He eventually served as the President-elect's transitional spokesperson before being designated as Chief Presidential Legal Counsel.

[19] Panelo is a member the Rotary Club of Makati Southwest chapter, a member of the Board of Trustees of the San Beda Law Alumni Association, and Secretary General of the Asean Law Association Golfers’ Club.