Benitez, whose relationship with the Manchester United manager was often fractious during his time in charge of Liverpool, was named Chelsea's interim manager on Wednesday following the sacking of Roberto Di Matteo.
"Of course, Rafa Benitez is very lucky because on his CV in two weeks' time he could have two world club titles to his name and had nothing to do with the teams," Ferguson said at his news conference ahead of Saturday's clash with Queens Park Rangers.
"Jose Mourinho won the treble at Inter. Rafa took over and they won the world title [in 2010] without having to do anything. He had nothing to do with the construction of the teams."
Di Matteo was sacked six months after leading Chelsea to Champions League and FA Cup triumphs and Benitez will take over an exciting team in third place in the Premier League.
They will also take part in the Club World Cup in Japan next month as European champions.
"That's why I really feel disappointment for Roberto - he could have an FA Cup, Champions League and Club World Cup on his CV. It's a pity for him," added Ferguson.
Ferguson and Benitez regularly indulged in mind games before their many north west derby clashes and in 2009 Benitez famously produced a hand-written list to back up his assertion that the Scot was never punished for verbally abusing match officials.
Benitez also once said the fixture list always favoured United, sarcastically joking that Ferguson organised the fixtures himself in his office.
Despite the friction between the two Champions League-winning managers, Ferguson hopes Benitez's luck holds out for his first game in charge of Chelsea against Premier League leaders Manchester City at Stamford Bridge on Sunday.
"Benitez has been trying to get a job for a long time," Ferguson said of the man who won the European Cup with Liverpool in 2005.
"I hope he is lucky on Sunday too.
"It happens time and time again when a new manager comes in they win their first few games. We've seen it before, it's a strange thing how it happens.
"Sometimes you wonder if it encourages chairmen at football clubs to make changes because they think if we get a new manager we'll win the next two or three games.
"History tells you that but you never know."
Ferguson said that despite the upheaval at Stamford Bridge and a run of poor form in the league, Chelsea were still very much in the title race.
"Certainly a few week ago we were thinking it looked like a three-horse race," added United great Ferguson, whose statue was being unveiled at Old Trafford on Friday.
"I don't think that is out of the question either because there are only a few points between the three teams anyway.
"Chelsea have got a big squad of players. There is a bit of youth throughout their team now, there is a sprinkling of youth coming through and a good blend of experience and young players. So there is no way you can possibly dismiss Chelsea."
