The United States-born striker signed for Litex Lovech last summer but they were expelled from the top flight after the coach ordered his players off the pitch after Johnsen and a team-mate were sent off during a derby against Levski Sofia.
Johnsen decided to leave after the club subsequently merged with CSKA Sofia, and made his Hearts debut off the bench in a 5-1 win over Inverness last weekend after FIFA ruled in his favour following a lengthy international clearance process.
The 24-year-old admits he has had a “bouncy” career having played in his father’s native Norway before spells in Spain and Portugal.
“It’s good, you see different cultures and you learn quicker,” said Johnsen, whose Hearts career continues against Partick Thistle in the Ladbrokes Premiership on Saturday.
“But I wanted to get some stability. I was in an unstable country so when the chance came to come to Hearts, I just jumped on it.
“The stability and knowing the coach wanted me to play here, I needed that. I had other options but I needed somewhere to work on my game and go further with my future. I have the opportunity to play here constantly as well.
On his spell in eastern Europe, he added: “The club wanted to make a new name, a new future for itself. I didn’t want to be part of that, and I decided it was best for me to leave the Bulgarian league.
“Last year I got a red card in a crazy game, we got taken off the field. I was only there for a year but so much stuff happened and I just decided it wasn’t stable. We were in the Europa League so it wasn’t a bad decision to go there, but I felt I needed stability. I had five or six coaches in a year.”
Hearts have come through a similarly uncertain spell under the ownership of Vladimir Romanov, which was followed by administration and relegation, to bounce back to the upper echelons of Scottish football under head coach Robbie Neilson and the stewardship of Ann Budge, who is set to hand over to fans in the coming years.
“I saw a lot of tendencies of Bulgaria when I saw the stuff that happened before at Hearts, and then I saw the turnaround in the last couple of years,” Johnsen said.
“So I liked the direction the club is going and I also felt the stadium, the new facilities, all the things told me yes. I couldn’t find any cons.”