West Brom name Pepe Mel as new coach
Betis' coach Pepe Mel reacts during the Spanish league football match Real Betis vs Malaga CF at the Benito Villamarin stadium in Sevilla on February 24, 2013
The 50-year-old Spaniard replaced Steve Clarke, sacked last month after a 1-0 defeat by Cardiff City left Albion two points off the relegation places.
But, under caretaker manager Keith Downing, the Baggies are currently four points above the bottom three.
Mel himself was sacked by Betis last month, with a 4-0 defeat by local rivals Sevilla helping seal his fate as the club failed to make good on last season's seventh-placed La Liga finish which took them into the Europa League.
Mel was appointed by Albion on a relatively short 18-month contract, but the Midlands side's sporting and technical director, Richard Garlick, told the club's website: "I'm delighted to welcome Pepe to the club.
"His appointment concludes an extensive recruitment process during which we have cast the net far and wide to identify the most suitable candidate to take the club forward.
"Pepe was a strong contender from the outset due to his impressive achievements and has emerged as our number one candidate.
"He is a forward-thinking coach whose teams are renowned for playing an attractive and positive style of football."
Downing will remain charge for Saturday's match away to Southampton, with Mel watching from the stands before taking charge of his first match as Baggies boss in the home game against Everton at The Hawthorns a week on Monday.
Under Downing, who will remain a member of the backroom staff, the Baggies took six points from four unbeaten league games.
"The board is extremely grateful to Keith, the coaching staff and players for their efforts over the past month, said Garlick.
"Keith will have an important role to play in supporting Pepe as he coaches in England for the first time."
West Brom will hope Mel can achieve similar success to that enjoyed by another former Liga manager, Mauricio Pochettino, at fellow Premier League club Southampton.
The Argentinian, who had been in charge of Espanyol, also had no track record in English football when he arrived at St Mary's in January last year but, under his guidance, the Saints are now an impressive ninth in the table.