The PM recorded three lines of dialogue for the show on Friday while at Downing Street.
Mr Blair will give tourism tips to Homer and the rest of his yellow family when they are in the country for a visit.
"The Prime Minister takes every opportunity he can to
promote Britain," a Downing Street spokesman said.
Mr Blair is the first British leader to appear in the comedy, although former US presidents Bill Clinton, George Bush and Jimmy Carter have all featured.
Just recently, footy star David Beckham missed out on being in the show - producers thought he wasn't famous enough!