Sebastien, who was an alternate selector for the last four years, replaces Courtney Walsh who stepped down from the selection panel last month after signing on as Bangladesh's new bowling coach, reports CMC.
Sebastien has played 92 first class matches and scored 4,934 runs with the highest score of 219.
He has managed the Windward Islands senior team for the last 12 years and has served as a director on the Windward Islands board for the last ten years.
"I want to thank the directors for approving my term as a selector. I have always been a team player and together with the other selectors, we will ensure the best West Indies team is selected at all times," said Sebastien here on Tuesday, manager for the West Indies A team to India in 2013 and Sri Lanka in 2014.
"Selectors have not always pleased everyone in the Caribbean but I am part of a team who will try the utmost to make Caribbean people happy".
The appointment was ratified at the Board of Directors meeting in Dominica earlier this month.
Sebastien's term as a selector is for two years.
