Jiranek was the first of a trio of deadline day moves at St Andrews, where Alexander Hleb and Chilean winger Jean Beausejour also linked up with boss Alex McLeish on Tuesday.
The former Czech international left his post as captain of Spartak Moscow to move to the Premier League, and the 31-year-old revealed a former colleague helped persuade him to swap Russia for England.
"I spoke with Radoslav Kovac who plays at West Ham United and he gave some great references," Jiranek told the club's official website.
"He said it was like a fairytale for him to be in the Premier League, playing in great stadiums in front of supporters that make a great atmosphere.
"Now I'm really excited about making my debut, I want to see and feel the atmosphere at the stadium and that great support from the Birmingham fans."
Jiranek arrives at the Blues with a wealth of experience behind him, having played in Euro 2004, the World Cup in 2006 as well as the top flights in Czech Republic, Italy and Russia.
The centre-half will provide competition to first-choice defensive pairing Scott Dann and Roger Johnson, who have formed a formidable partnership since helping the club secure promotion to the top flight and then preserving their status.
And Jiranek says he cannot wait to taste the unique experience of English football, which he says was a massive draw in making the move from the Russian capital.
He went on: "I know that Jiri Jarosik used to play for the club and I know they have a good coach and a great team who did very well last season.
"I also know Birmingham is the second biggest city in England and the club has brilliant supporters who are crazy about their team.
"I'm very happy to sign a contract with Birmingham City. As soon as I saw the stadium and the city I knew it was the right move for me."
Jiranek indicated he was aware he may not feature immediately in McLeish's first team plans such is the solidarity of the Johnson and Dann partnership, but the former Reggina man said he is prepared to fight for his place.
He added: "I was captain of Spartak Moscow so this move was a difficult one but now I'm very happy and I hope to bring more strength to the team, I've always been a warrior so I think I can help my new team-mates to more victories.
"I think I have enough quality to make an impression but it's a question of time and taking my chances when they come."