However, there has been a decline of 5.76 per cent in the growth rate of population in the state in comparison to the previous decade's growth rate.
From 16.61 crore in 2001, the state's population has increased to 19.95 crore in 2011 at a rate of 20.09 per cent as against 25.85 per cent growth rate in the previous decade.
"As per the provisional count, the population of UP is about one-sixth (16.5 per cent) of total population of India and has increased by more than 3.3 crore," director of Census Operations UP Neena Sharma told reporters here.
The population comprises of 10,45,96,415 males and 9,49,85,062 females and the sex ratio has improved, she said.
"The percentage decadal growth during 2001-2011 has registered a decline of 5.76 percentage points from 25.85 to 20.09 per cent," Sharma said.
She said UP continues to be the most populous state in the country, with a population more than that of Brazil.
However, the growth rate of the population in the age group of 0 to 6 years is minus 6 per cent, as it is down from 3.16 crore in 2001 to 2.97 crore in 2011.
While the growth rate of male population in this age group is minus 5.18 per cent, it is minus 6.88 per cent in the case of females.
Among districts with maximum population, Allahabad is at the top with a population of 59.59 lakh followed by Moradabad at 47.73 lakh, Ghaziabad at 46.61 lakh, Azamgarh with 46.16 lakh people and Lucknow with a population of 45.88 lakh.
Mahoba in Bundelkhand region has the lowest population of 8.76 lakh followed by Chitrakoot 9.9 lakh, Hamirpur 11.04 lakh, Shravasti 11.14 lakh and Lalitpur 12.18 lakh.
Among cities, Lucknow continues to be the most populous with a total population of 28.15 lakh followed by Kanpur at 27.69 lakh.
Despite the increase in population, the percentage decadal growth rates of the most populous districts, including Allahabad, Moradabad, Ghaziabad, Azamgarh and Lucknow have declined during 2001-2011 as compared to 1991-2001.
As per the provisional count, the overall sex ratio of the state has increased by 10 points from 898 in 2001 to 908 in the last decade.
Jaunpur, reporting 1018 female as against 1000 males, has the highest sex ratio, which it the lowest in Gautam Buddha Nagar and Kanpur at 852.
Child sex ratio between the age group of 0 to 6 years has declined from 916 females per 1000 males in 2001 to 899 in 2011.
An increasing trend in the child sex ratio in this age group has been witnessed in Hardoi, Ballia, Siddharth Nagar, Kushinagar, Bijnor and Sonbhadra.