Before he became one of boxing’s most dominant heavyweight champions and even longer before he entered the decidedly more treacherous arena of Ukrainian politics, a teenage Vitali Klitschko led tourists visiting Kiev on excursions through the capital. He was 16 and it was his first paying job.

Thirty years later Klitschko, who was elected mayor of Kiev in 2014, is still making his pitch for the hometown dear to his heart with the enthusiasm of a bright-eyed tour guide. The city was the center of the sporting universe over the past week as it played host to Saturday’s Champions League final between Real Madrid and Liverpool, rolling out the red carpet for tens of thousands of tourists, and Klitschko was front and center throughout, walking the streets and snapping selfies with the visiting hordes when not working to resolve the airport imbroglio that imperiled many ticket-holders’ flights.

It’s roughly eight hours before kickoff when we meet in his office on the ninth floor of the Kiev City State Administration building on the Khreshchatyk, the main drag in the city center. He’s just finished a call with Liverpool mayor Joe Anderson, playfully ribbing the card-carrying Everton fan for not making the trip. Nearly six years have come and gone since he retired from boxing on top after a 15th successful heavyweight title defense, but the enviably fit 6ft 7in Klitschko looks as if he could still give anyone in the division a tough night.

“The biggest challenges are fixing the problems, to put all the puzzles together,” the 46-year-old says of playing host to the world’s biggest annual sporting event. “It’s a big honor for us and also a big responsibility with more than 50,000 visitors from outside the country. But everybody’s happy and there’s a great atmosphere. Many people ask me for a prediction for tonight: who will be the winner? The winner today is the city of Kiev and country of Ukraine. We’re the winner because it’s one more chance to present our city to the world.”

The day before marked exactly four years since Klitschko was tabbed for mayor with 57% of the vote in a snap election, before earning re-election the next year’s scheduled contest with a 66.5% majority. The results have by all accounts been mixed.

“I tell you very openly: it’s much easier to be the heavyweight champion of the world than to be the mayor of Kiev,” he says. “Because [in politics] there are no rules. It’s hitting you in the back. It’s hitting you under the belt line. It’s really tough. And you are responsible 24 hours a day, seven days a week.”

When I ask him to assess his record – to compare his achievements with his ambitions when he took office in 2014 – Klitschko comes to life, rising from his boardroom table and walking towards a newspaper article pinned to a corkboard on the wall. The accomplishments are printed in blue and he proudly reads them off: the reconstruction of 500km of new roads to the European standard, the shuttering of illegal kiosks that infested parks and streets. The remaining challenges, in red, include further improvement of municipal services, fighting back against companies that build illegally and fixing the city’s nightmarish parking situation.

Klitschko, who holds a PhD in sports science, earned $60m during his boxing career and could have easily retired into a life of comfort. But he was compelled to enter the cutthroat world of Ukrainian politics – formally entering the fray with a second-place finish in the Kiev mayoral race in 2006 – out of a deep love for his country and a potential for greatness he believed went untapped.

Vitali Klitschko with his brother Wladimir after a successful title defence in 2012. Photograph: Alexander Hassenstein/Bongarts/Getty Images

“I remember the Soviet Union and when the Iron Curtain fell down in 1991,” he recalls. “I was just 20 years old and everybody had a dream to live in a modern democratic society, in a modern country. More than 15 years passed and nothing changed. There’s a saying I like very much: if you want a thing done well, do it by yourself.”

He pressed forward while still reigning as WBC heavyweight champion, winning election to parliament in 2012 as a member of the Ukrainian Democratic Alliance for Reform (Udar) party, which he founded, and became one of the country’s most visible political leaders during the pro-western revolution two years later. Some even believed he would succeed Viktor Yanukovych as president, but he instead backed Petro Poroshenko to avoid splitting the vote and won the mayoral election in 2014.

The overarching philosophy of Klitschko’s political theory, as he explains it, is eliminating the corruption deeply embedded in the system.

“The Soviet system is how everything here works,” he explains. “It’s very difficult to break the system. The system is big and inflexible, uneffective and also corrupt. And that is our main goal, to change the system, to break the system, to make it modern.

“We open the mayor’s office, we open all commissions, we open our budget. Every journalist and every citizen right now know all incoming and spending from our budget. It’s very important. Transparency is our main goal. Also our main weapon against corruption. The money before was in the shadows, right now it’s open and working for the community. It’s not easy because some people who are inside the system, defend [themselves] and defend the system.”

Sport remains dear to Klitschko’s heart – he’s at the gym at six every morning and at the office by nine – and he still makes time to watch the big fights, particularly the division he dominated so ruthlessly. He believes Britain’s Anthony Joshua, the current WBA and IBF heavyweight champion, “has all the skills” to be one of the division’s greats, but won’t get to the next level until he goes through with a unification bout against American Deontay Wilder, who holds the WBC title.

“The question always when there are many world champions is: who is the strongest one?” he says. “That’s why to fight Wilder is very good. Right now Joshua is a champion. With this fight, he can be a star.”

Klitschko’s record in the ring was formidable. He won 45 of his 47 professional fights (including 41 by knockout) and made three separate title reigns, becoming the only heavyweight champion ever to hold the title in three different decades. A devastating puncher with a granite chin, he went through his entire career without getting knocked down or taking a standing eight count. It’s not a stretch to suggest that he would have finished his career undefeated if not for bad luck with injuries: both of his defeats, including a famous 2003 scorcher with Lennox Lewis, came on injury stoppages while he was ahead on the scorecards. Yet more than fame and fortune, Klitschko believes that’s boxing offered essential preparation for his second career.

“Sports gave me the strengths I use every day,” he says. “For one, it’s very important to have a good team around you. Early in my career I was told if you want to be the best in the sport, take the best coach, take the best promoter, take the best manager, take the best lawyer and with the best team you will be automatically be the best. Exactly the same. I’ve tried to find the good people, good people who will take responsibility. Because as mayor no matter how strong you are yourself, no matter how big muscles you have, alone you can do nothing. You need good people around you.

“Secondly, you have to know exactly where to go. To have the will and to have courage to arrive there. That’s exactly the same way I approached my boxing career.”