The champions chose speed as their theme for their Monday parade, in which their 3,600-strong troupe honored the memory of national idol Senna, killed in a crash at the San Marino Grand Prix 20 years ago.
Unidos da Tijuca also paid tribute to Olympic sprint champion Usain Bolt, featuring a runner dressed in Jamaican kit during a parade which wowed 72,000 spectators at a packed Sambadrome.
The elite dance school, whose routine featured a Formula One car and mini race track, just pipped nearest rivals Salgueiro by one tenth of a point to land their third title in the past five years.
After the jury announced the result, having judged criteria such as samba style, costumes and floats, some 10,000 supporters of the champions gathered at their headquarters for an all-night celebration party.
Imperio da Tijuca were meanwhile relegated from the elite section after coming last.
Although this year's Carnival officially ended Tuesday night, the top six schools will appear again in Saturday's Champions' Parade.
One of Rio's oldest samba schools having been formed in December 1931, Unidos da Tijuca represent several slums or favelas in the western Tijuca area.
Some four million people, including 918,000 tourists, participated in this year's Rio Carnival, the world's biggest street party, featuring some 500 street parades as well as the two nights of elite parades.