The Bill Kenwright production has been running continuously in London for 24 years, and announced earlier this month that the show would close after a final performance on 27 October, saying "this is the end of a chapter, but by no means the end of Blood Brothers."
But the West End chapter has extended a little - it will now close on 10 November.
Blood Brothers was first seen as a comprehensive school production in Russell's native Liverpool in 1981, before receiving a professional premiere at the Liverpool Playhouse and subsequent West End transfer to the Lyric Theatre, where it had a brief run, two years later.
In 1988, Kenwright revived the musical to award-winning effect at the Albery Theatre, transferring it in January 1991 to the Phoenix Theatre, where it has been running ever since.
A separate touring production, starring former Wet Wet Wet lead singer Marti Pellow, continues an extensive UK-wide schedule.
The current West End cast of Blood Brothers features Vivienne Carlyle (as Mrs Johnstone), Philip Stewart (Narrator), Mark Rice Oxley (Mickey), Paul Christopher (Eddie) and Abigail Jaye (Mrs Lyons). It is still unclear what production will follow in the 1000-seat Phoenix Theatre, though Starlight Express has been rumoured as a replacement.