World-beating marathon runner Paula Radcliffe also raced ahead of "Becks" who fell to fourth place from first in the affections of Britain's youngsters.
Radcliffe was listed second and Flintoff, who helped England's cricket team beat Australia in the Ashes tournament last month, came third.
The study, by supermarket chain Tesco, also found that one in three girls said football was their favourite sport, ahead of traditional games such as netball and rounders. Of the boys, more than two-thirds preferred football.
Lampard, the free-scoring Chelsea and England midfielder, headed a list of 10 top sporting personalities for 2005. Other favourites included multiple Tour de France winner Lance Armstrong in eighth place and Olympic gold medallist athlete Kelly Holmes in fifth.
Commenting on the survey, Lampard said: "I'm delighted to have been voted the number one sports hero by the UK's kids.
"I'm passionate about getting kids involved in sport and it's great to think that while I'm out there playing, I'm also going some way to inspire the next generation of footballers - male and female."