"I'm no longer coach of Litex," Penev said after Litex's 2-1 win over Ludogorets. "I'll negotiate with Bulgarian Football Union's president Borislav Mihaylov later this week."
Bulgaria have been looking for a new coach since the departure of German Lothar Matthaeus last month.
Matthaeus, who became the first foreigner to coach Bulgaria since 1966 just over a year ago, achieved little success with the team during the Euro 2012 qualifying campaign.
Bulgaria failed to score in any of their four home games and finished bottom of Group G with five points from eight matches, their worst ever performance in major tournament qualifying.
Litex immediately announced Atanas Dzhambazki as Penev's successor.
"Everything is clear," said Litex owner Grisha Ganchev.
"Dzhambazki is our new coach and Lubo Penev is the new national team's coach."
Dzhambazki previously coached four clubs in the Bulgarian top flight including Slavia Sofia, Montana and Botev Vratsa.
"We hope that Dzhambazki will lead our team to third consecutive title," said Litex president Trifon Popov.
Former CSKA Sofia coach Penev, considered one of the best coaches in the Balkan country, led Litex to the league title last season.
The 45-year-old former Bulgaria striker boasted a remarkable scoring record in the Spanish league, netting more than 150 goals for Valencia, Atletico Madrid, Compostela and Celta Vigo.
Penev finished his spell at Litex in style by inflicting surprise leaders Ludogorets's first defeat of the season.