Zamolodchikova began gymnastics at the age of six. In 1999 she participated in her first major senior competition, the World Gymnastics Championships. She won the gold in vault and the bronze in the all-around.
Just days before the 2000 European Championships in Paris, her father died as a result of radiation exposure from the Chernobyl accident. Zamolodchikova led her team to the gold medal and earned individual silvers in the all-around and vault finals and a bronze on the beam.
Zamolodchikova was selected as a member of the Russian gymnastics team at the 2000 Summer Olympics in Sydney. Although initially she did not qualify into the all-around or vault finals, she earned spots in both when Elena Produnova withdrew from the all-around and Svetlana Khorkina decided to give up her spot to Zamolodchikova. In the team competition, the Russian team was leading after the preliminary rounds, however, four Russian gymnasts made mistakes in the finals, costing them the gold. Zamolodchikova was one of the four, slipping off the beam as she took off for a Rulfova and narrowly missing her head.
After two apparatus in the all-around, Zamolodchikova was in first place with her stronger exercises still to go. However, she lost her chances of an all-around medal with a fall on the floor exercise on her simplest tumble. On a night where many gymnasts made uncharacteristic errors, she eventually finished 6th. Had she scored the same in the all-around as she did for her team finals performance, her total would have been enough to win her the gold.
Zamolodchikova won gold on both the vault and floor, thus becoming a two-time Olympic champion. During vault finals, Khorkina sat in the stands, cheering loudly for her teammate, for whom she gave up her spot. Khorkina was leading in the floor finals until Zamolodchikova performed: both were vying for a second gold.
Zamolodchikova won the 2002 World vault title and a European all-around bronze medal in 2004, in addition to numerous other awards.
Zamolodchikova, also a lieutenant in the Russian Army, competed in her second Olympic games in 2004. The Russian team won a bronze medal, and Zamolodchikova just missed out on an individual vault medal, placing fourth behind Monica Roşu of Romania, Annia Hatch of the United States, and a fellow Russian, Anna Pavlova.
At the 2005 World Championships in Melbourne, she placed fourth in both vault and floor finals. In the floor finals, she performed four extremely difficult tumbling passes, landing each one cleanly, but did not successfully compete all of her dance combinations. Her start value was lowered as a result from 10.0 to 9.7, and she scored a 9.162, placing her behind Americans Alicia Sacramone and Nastia Liukin, and Dutch gymnast Suzanne Harmes. Zamolodchikova's low score was unpopular with the crowd, who appeared to think she should have won bronze. She scored an average of 9.318 on her two vaults, finishing behind Cheng Fei of China, Oksana Chusovitina of Uzbekistan, and Alicia Sacramone of the U.S.
Although many gymnasts retired as the new code was introduced, Zamolodchikova decided to continue competing. She struggled at her first competition of 2006, the American Cup, partiularly on bars where she had a fall. An injury prevented selection for the 2006 European Championships in Volos, Greece.
Zamolodchikova helped the Russian team to a bronze medal in the team event, their first at world level since 2001, and qualified to vault finals where she was fourth. In 2006, she also competed her new vault skill, a Yurchenko laid out half-on, half-off which has an A-score of 5.6P in the new code.
After the World Championships, she competed in a few World Cup competitions winning a bronze medal on vault in the DTB-Cup in Stuttgart and two silver medals on vault and on floor in the Glasgow Grand Prix. She crowned her year with a bronze on vault at the World Cup Finals in São Paulo, Brazil.
At the 2007 World Championships in Stuttgart, Germany, her teammate Ekaterina Kramarenko ran up and touched the vaulting table but stopped and received a 0. Zamolodchikova performed a solid vault, but the Russian team had already ended up eighth (last). In the event finals, she fell on her second vault, and finished again in eighth.
Zamolodchikova continued training in 2008 in hopes of making the Russian Olympic team for the third time, but a back injury prevented her from a better showing and she failed to do so. Instead, she competed in various World Cup events, narrowly missing a medal on floor at the 2008 World Cup Final in Madrid, where she finished fourth.
Zamolodchikova made her last competitive appearance at the 2009 University Games in Belgrade. She began her judging career at the 2009 DTB Cup in Germany.
1999 Worlds: "Baby Elephant Walk" - Henry Mancini
2000 Olympics: "Who's That Creepin'?/Daddy-O" - Big Bad Voodoo Daddy / Hipster Daddy-O and the Handgrenades
2002 Worlds: "Crazy Benny/Breathe" - Safri Duo / Moist
2004 Olympics: "Egyptian Symphony" - Mozart
2005 Worlds: "Crazy Benny" by Safri Duo and "Breathe" by Prodigy.