The royal command on the Wasant appointment took effect on Wednesday.
Wasant was elected via a peer vote in August to replace Chut Chonlavorn who stepped down after serving three years in office.
The process to issue the royal command took longer than usual due to complaints related to the legal technicality of the peer vote and the justification for Chut to relinquish his position.
Chut left the court presidentcy in the wake of a video clip controversy although he would remain one of the nine justices.
The controversy erupted in 2010 following the posting of five video clips on YouTube. One of the clips showed the edited version of a judicial debate held in private chamber releated to the Democrat Party dissolution case.
Chut’s private secretary Pasit Sakdanarong was suspected to be involved in the controversy. Pasit was later cleared of all charges.