In a statement, West Bromwich Albion's Sporting and Technical Director Richard Garlick said Mel's appointment 'concluded an extensive recruitment process during which [the club has] cast the net far and wide'.
"Pepe was a strong contender from the outset due to his impressive achievements and has emerged as our No. 1 candidate.
"He is a forward thinking coach whose teams are renowned for playing an attractive and positive style of football.
"The Board is extremely grateful to Keith, the coaching staff and players for their efforts over the past month, which has yielded six points from four unbeaten league games."