Ex-Sofia coach takes over at Slavia
The 48-year-old Velev has agreed to sign a one-year contract with the seven-times Bulgarian champions with an option to extend it for a further year.
Velev comes in for Velislav Vutsov, who he also replaced as Levski coach in 2008 when he took The Blues to the league title.
"It's not so pleasant to part with Vutsov but I want some changes," said Slavia president Ventsislav Stefanov. "I want a stronger team for the club's 100th anniversary (in 2013) and we should begin to build the foundation of it."