CSKA of the late 1980s was the football "alma mater" to several Bulgarian players like Hristo Stoichkov who made it to the international team in the 1990s.

During those days Lubo's teammates included defender Trifon Ivanov, winger Emil Kostadinov, and striker Hristo Stoichkov.

Penev made his debut for the Bulgaria national team on 20 May 1987, playing as a starter in the 3–0 home win over Luxembourg in a Euro 1988 qualifier, before being substituted by Petar Aleksandrov during the second half.

[citation needed] In March 2009, he succeeded his uncle Dimitar Penev as manager of CSKA Sofia and under his guidance the team qualified for the group stages of the UEFA Europa League, defeating FC Dynamo Moscow – 2–1 on aggregate.

After the lost game against Minyor Pernik he withdrew nine players from training sessions for breaking the club's rules, this led to the conflict with the owners.

Under his management, Bulgaria's fortunes picked up and the team put in credible performances against Italy, Denmark and the Czech Republic in the qualifications for the 2014 FIFA World Cup.

[4] The sudden financial troubles of the club, however, led to the quick termination of his contract in early July after only one game (4–0 home victory against Libertas at the first qualifying round for UEFA Europa League).

[6] On 20 November 2014, Penev was sacked by Bulgaria National Team following a run of poor results that culminated in a frustrating 1–1 home draw with Malta.

In late September 2016, national team coach Ivaylo Petev agreed to a managerial contract with Dinamo Zagreb and therefore resigned.

He was appointed as manager of CSKA Sofia for a third time on 8 February 2019,[10] but resigned in early May due to disagreements with the club's board.

[14] In March 2023, he took over as head coach of relegation-threatened Hebar Pazardzhik, with the aim of securing the club's place in the top flight of Bulgarian football.