Xi and other top Chinese officials visited Mao’s mausoleum on Monday – located in the heart of Beijing in Tiananmen Square – and bowed three times to the late leader’s statue, reported official news agency Xinhua.
He also paid respects to the remains of Mao, whose embalmed body is kept in a glass display case at the memorial hall.
The last time a Chinese leader bowed to the statue of the “Great Helmsman” was six years ago, when Xi commemorated 120 years since Mao’s birth.
The Communist leadership tightly controls public discussion of history and seeks to use Mao’s legacy to shore up its support.
But Mao, who died in 1976, remains a controversial figure in China and his legacy during the Cultural Revolution has shadowed the country’s history.
There are still no official figures on how many people were killed or purged in China during the Cultural Revolution, which began in 1966.
Some historians say the number of dead could be as high as two million – still less than the 40 million people believed to have died during the famines also blamed on Mao’s disastrous policies in the late 1950s
The move to honour the founder of the People’s Republic of China comes as the country readies itself for a day of tightly choreographed festivities, including a large military parade and the release of 70,000 doves.
The anniversary is meant to showcase China’s extraordinary rise from the ravages of war and famine to a modern, powerful nation-state.
The celebration comes at a difficult time for the Chinese president.
The US-China trade dispute threatens to pummel the global economy, while African swine fever has sent the price of pork – the country’s staple food – soaring.
Months of unrest and pro-democracy protests in semi-autonomous Hong Kong also threaten to upstage Tuesday’s celebrations, with fierce clashes between protesters and riot police erupting on Sunday.
Democracy activists in the city have vowed to ramp up their nearly four-month-long campaign ahead of National Day, which Hong Kong protesters have dubbed a “Day of Grief”.
On Monday morning, Xi and other leaders of the Communist Party of China also attended a wreath-laying ceremony to honour national heroes on Tiananmen Square.
A choir of children in crisp white shirts and red neckerchiefs sang before Xi approached the Monument to the People’s Heroes – a tall obelisk in the middle of the square – where baskets of flowers decorated with red banners were placed.
“A promising nation must have heroes, and a country with future prospects must have pioneers,” said state-run CCTV in a broadcast of the ceremony, quoting Xi.