It beat out competition from THE BEATLES' songs HEY JUDE and LET IT BE to land the number one spot in the poll, in which 7,000 listeners cast their votes.
In fourth place was ONE by Irish band U2 followed by ROBBIE WILLIAMS' ANGELS.
Virgin Radio's BEN JONES says of Lennon, "His writing, especially with Paul McCartney, is possibly the country's greatest ever musical export and he clearly still holds a special place in the nation's heart."
2005 saw the 25th anniversary of Lennon's death. He was killed outside his New York apartment by a crazed fan on 8 December 1980.
The Top 10 favourite songs are:
1. IMAGINE - JOHN LENNON
2. HEY JUDE - THE BEATLES
3. LET IT BE - THE BEATLES
4. ONE - U2
5. ANGELS - ROBBIE WILLIAMS
6. BOHEMIAN RHAPSODY - QUEEN
7. STAIRWAY TO HEAVEN - LED ZEPPELIN
8. EVERY BREATH YOU TAKE - THE POLICE
9. HOTEL CALIFORNIA - THE EAGLES
10. YOU'RE BEAUTIFUL - JAMES BLUNT.