Fillo began his career with 2. Liga club Viktoria Plzeň and helped the club to promotion to the First League during the 2004–05 season. In his first full season in the top flight, he made 29 appearances and scored five goals, as Plzeň narrowly avoided relegation. He played 15 matches and scored five goals during the 2007–08 season, before making his last appearance for the club in December 2007.
Fillo signed a five-year deal with NorwegianTippeligaen club Viking in 2008, breaking the transfer record at the club. He made his debut for Viking on match day one of the 2008 season, assisting the winning goal and being voted man of the match in a 1–0 victory over Strømsgodset IF. He scored his first goal for Viking in a 1–0 victory over Tromsø IL on match day four. He appeared consistently during the 2008 season, making 28 appearances and scoring 8 goals. He made 25 appearances and scored three goals during the 2009 season and played in Viking's UEFA Cup qualifiers, which ended with a second round defeat to Honka. In the 2010 season, Fillo made only 15 appearances, but scored five goals, including a hattrick against Odds on 4 July 2010.
Return to Viktoria Plzeň
Fillo re-signed for Viktoria Plzeň on a four-and-a-half-year contract during the 2010–11 season and made 12 appearances, scoring one goal. He won the first silverware of his career, having helped Plzeň to the First League title and he also won the 2011 Czech Supercup with the club. Fillo began his 2011–12 season by making appearances in the Champions League qualifying stages, through which Plzeň progressed to the group stage. He appeared as a substitute in three of Plzeň's six group stage games, coming on against AC Milan, Barcelona and BATE Borisov. When the league season started, Fillo found himself out of favour. He made a total of 9 appearances during the 2011–12 season, scoring one goal, helping Plzeň to a third-place finish and Europa League qualification. Fillo was back in the team at the start of the 2012–13 season for Plzeň's Europa League qualifiers. He made 27 appearances during the 2012–13 season, but failed to score, though he picked up another First League winners' medal. Fillo spent the 2013–14 and 2014–15 seasons away on loan and departed the club in June 2015. Fillo made 56 appearances and scored three goals in his second spell with Plzeň.
Fillo joined fellow Gambrinus Liga club Mladá Boleslav on loan after the winter break in February 2012 and made 17 appearances, helping the club a fourth-place finish and to Europa League qualification. He rejoined Mladá Boleslav on loan in September 2012, making 10 appearances before returning to Plzeň prior to the winter break. Fillo made 27 appearances and scored three goals across his two spells with Mladá Boleslav.
In July 2013, Fillo agreed a season-long loan with English League One club Brentford, linking up with Uwe Rösler, his former manager at Viking. He made his debut as a substitute in the first game of the season, coming on for Conor McAleny after 71 minutes of a 1–1 league draw at Port Vale. In the following game, he scored on his full debut, bagging the second goal in a 3–2 League Cup first round win over Dagenham & Redbridge. Fillo was dropped from the team in October 2013 and new manager Mark Warburton indicated in late December that he would hold talks with Fillo over his future. Fillo was made available for loan on 19 February 2014, but staked a claim for a first team appearance with a hattrick in a 6–3 Development Squad defeat to Charlton Athletic on 3 March. In a forgettable 2013–14 season, Fillo scored one goal in just 9 appearances for the Bees. He finished the Development Squad's 2013–14 season as the team's leading scorer, with four goals in six appearances.
1. FK Příbram (loan)
Fillo joined First League club 1. FK Příbram on loan for the duration of the 2014–15 season. He made 27 appearances and scored two goals before returning to the Doosan Arena.
In July 2015, Fillo joined First League club FK Teplice on a three-year contract. Over the course of two-and-a-half seasons, he made 73 appearances and scored 22 goals and departed Na Stínadlech in December 2017.
On 29 December 2017, Fillo joined Czech First League club FC Baník Ostrava on a permanent contract for an undisclosed fee. In what remained of the 2017–18 season, he made 14 appearances.
International career
Fillo represented the Czech Republic at youth level and was U21 captain. He won three caps for the senior team in 2009.
