The Portuguese winger has struggled to make an impression at Old Trafford since his £7.4m move in August 2010. The 22-year-old has played seven times for the first-team, and spent an injury-ravaged spell on loan to Besiktas last season.
But Ferguson is hopeful that a return to Portugal will do Bebe good.
Speaking to MUTV, Ferguson said: "We feel the boy has got to get good experience at a better level than our reserve team.
"He's gone to Rio Ave who are fifth in the Portuguese league at the moment - they have a young coach [Nuno] who has a very good reputation.
"Bebe has done quite well in the last two or three months. He got a cruciate knee injury when he was on loan in Turkey last season and that derailed him for a bit. Coming back from these injuries takes time but he's started to develop quite well.
"Hopefully his spell in Portugal, where he is from anyway, could help him."
Ferguson reportedly admitted Bebe was the first player he's ever bought without watching play live, and his limited impact on the first-team has led some to label the former-Vitoria winger a Manchester United flop.
The young attacker has six caps for Portugal under-21s, and returns to his home country to play for the first time since he left Vitoria de Guimaraes in 2010.
Manchester United face West Ham at Upton Park this weekend in the FA Cup third round.