Janečková first appeared in January 2002 at the Nordic Junior World Ski Championships 2002 in Schonach . There she finished 30th in the sprint and 14th place over 5 km freestyle. At the Rollerski World Championships in 2002 in Monte Cervino , she won the bronze medal in team races and with the relay. She ran her first World Cup race in January 2003 in Nové Město , which she finished in 45th place over 10 km freestyle. At the Junior World Championships in 2003 in Sollefteå , Sweden , she was tenth both over five kilometers in the classic technique and in the mass start race over 15 kilometers. At the following Nordic World Ski Championships in Val di Fiemme , she came in 47th place in the 10 km skiathlon and eighth place with the relay. She took her first World Cup points at the end of the 2003/04 season in Pragelato with 25th place over 15 km freestyle. At the Junior World Championships in 2004 in Stryn , Norway , she was fifth over five kilometers in free technique and was able to win the relay silver with her Czech teammates. At the Nordic World Ski Championships in Oberstdorf in 2005 , she won 33rd place over 10 km freestyle, 11th place with Helena Erbenová in the team sprint and sixth place with the relay. In the following season she finished in her first Olympic participation in Turin, 27th place in the 30 km mass start race, 23rd place in the 15 km skiathlon and sixth place with the relay. At the beginning of the 2006/07 season she reached her first and only podium finish in the World Cup with third place in the relay at the World Cup in La Clusaz . In the further course of the season she came at the Nordic World Ski Championships 2007 in Sapporo on 32nd place over 10 km freestyle, on 21st place in the 30 km mass start race and on fifth place with the relay. At the following U23 World Championships in Tarvisio , she won the bronze medal in the 15 km skiathlon. From 2007 to 2012 she also took part in the Slavic Cup races. She won three races and reached sixth place in the overall standings in the 2008/09 season. She finished the 2007/08 Tour de Ski in 35th place. Her results at the Nordic World Ski Championships 2009 in Liberec were 32nd place in the 15 km skiathlon, 43rd place over ten kilometers in classic technique, twelfth place with the relay and ninth place together with Kamila Rajdlová in the team sprint. In the 2009/10 season she finished 24th at the Tour de Ski 2009/10 . At the 2010 Olympic Winter Games in Vancouver she came in 40th place in the 30 km mass start race, 32nd place over 10 km freestyle and 12th place with the relay. At the end of the season she reached her best individual placement in the World Cup with 16th place in the 30 km mass start race in Oslo . She finished the Tour de Ski 2010/11 on 27th and the Tour de Ski 2011/12 on 40th place. At the 2011 Winter Universiade in Erzurum , Turkey , she was fourth in the mass start race over 15 kilometers and seventh in the pursuit race over ten kilometers. At the Nordic World Ski Championships in Oslo in 2011 she won 22nd place in the 15 km skiathlon, 20th place in the 30 km mass start race and 12th place together with Eva Vrabcová-Nývltová in the team sprint. She ran her last World Cup race in February 2012 in Szklarska Poręba and finished 43rd over 10 km classic. After the 2012/13 season, in which she still competed in the Slavia Cup and FIS races, she ended her career.
Janečková took part in a total of 38 individual World Cup races and came in 13 times in the points.
Participation in World Championships and Olympic Winter Games
Olympic games
2006 Turin : 6th place in relay, 23rd place 15 km skiathlon, 27th place 30 km freestyle mass start
2010 Vancouver : 12th place relay, 32nd place 10 km freestyle, 40th place 30 km classic mass start
Czech Republic
Kremnica