A pre-performance video aired on Monday night showed that Nemcova had been rehearsing the foxtrot with partner Dmitry Chaplin when she learned of the March 11 earthquake and tsunami.
"My heart was breaking knowing what people in Japan are going through," she said, adding that it was hard to focus on dancing when there was so much suffering in the country.
"I would like to dedicate this foxtrot to every person who has been suffering in Japan and every person who has been impacted by this tragedy."
Nemcova, who lost her fiancé in the Boxing Day Tsunami in 2004, had previously spoken of her "agony" over the natural disaster in an interview with Piers Morgan Tonight, adding: "One thing is true - [don't] give up. There are many stories of hope and loved ones being found.
"One thing which I have seen personally amongst the disasters is [that] there is so much unconditional love [with] people being willing to sacrifice their own lives for others."
Dancing with the Stars continues next Monday at 8/7c on ABC.
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