Mr Lampard, who is now a children's author himself, is also reprising his role as a "Reading Star" for one of the charity's popular school literacy programmes.
Premier League Reading Stars is a reading intervention that uses football to inspire young people to read more and to improve their literacy skills. In primary schools, the intervention is aimed at year 5 and 6 pupils who are struggling to reach the expected levels of literacy and are in danger of falling behind.
It offers resources and activities, including online challenges posed by 20 Premier League footballers – one from each club. The footballers have also all recorded videos discussing their favourite books.
Mr Lampard was Chelsea's Reading Star last year and is reprising the role in 2015 on behalf of his new club, Manchester City.
Alongside the other 19 footballers, he has laid down his three challenges and appears in a video on the National Literacy Trust website.
The 10-week Reading Stars intervention currently involves more than 30,000 children in 1,000 schools and libraries, with Premier League-branded materials available, including certificates, wristbands, reading journals and wall charts. Schools can still sign up to get involved in the scheme.
Mr Lampard, who published his own series of books – Frankie's Magic Football – after requests from his two daughters for stories about football, said: "I am delighted to take up the role as an ambassador for the National Literacy Trust and help to further their work in supporting disadvantaged children across the UK to discover the joy of reading and develop their literacy skills.
"Reading should be a pleasure no matter what age you are, and Premier League Reading Stars is a proven way of getting children to enjoy books. It's very easy for young people to get distracted by computer games and television but the importance of getting children to enjoy reading was the inspiration behind my own books. Whether you're reading with your kids or just enjoying a good book on your own it's a wonderful experience and one of life's great pleasures."
Jonathan Douglas, director of the National Literacy Trust, added: "We are honoured that Frank Lampard has taken the decision to further his work with us at the National Literacy Trust and become an ambassador.
"As a father, footballer and author, Frank's experience and enthusiasm for getting kids reading will bring a crucial focus to our national literacy campaign. We are excited to have him on board to help motivate thousands of children to discover the joy of reading and reach their full potential."
The National Literacy Trust is a national charity dedicated to raising literacy levels in the UK, with a focus on projects in the poorest communities and campaign work to make literacy a priority for politicians and parents. Much of its work is aimed at supporting schools.
To find out more about Mr Lampard's reading challenges and favourite books, visit www.
literacytrust.org.uk/plrs_2015/manchester_city
For details on the Premier League Reading Stars scheme, go to www.literacytrust.org.uk/premier_league_reading_stars/about_plrs