Ferguson cast doubt on whether Ferdinand would accept Roy Hodgson's call for the World Cup double-header against San Marino and Montenegro after expressing concern about disruption to the meticulous way the 34-year-old prepares for games.
However, after Ferdinand produced another controlled display, including setting up Wayne Rooney's winner in the 1-0 triumph over relegation-haunted Reading, Ferguson confirmed the defender would report for duty at St George's Park on Monday.
"Rio will be joining up," said Ferguson.
It is believed Hodgson has spoken to the United boss to offer assurances about how the player will be treated, which may include not using him in the San Marino game.
Saturday night's evidence showed why England want him involved in Podgorica though, as Ferdinand sauntered upfield before slipping a pass to Rooney - whose 21st-minute effort deflected in off Alex Pearce.
"He broke into the midfield very well," said Ferguson. "He has always been good at that. He doesn't do it as much as he used to of course but it paid off for us."
United are clearly concerned about the effect this international break could have on their season considering they travel to Sunderland on March 30 for a lunchtime kick-off, and Chelsea 48 hours later for their FA Cup quarter-final replay.
"We are making arrangements for some players to fly home by privately hired jet after their matches to make sure they get home as quickly and as smoothly as possible," said Ferguson.
"Tiredness is a great leveller but we'll do our utmost to make sure we field the freshest possible teams. Private planes are going to cost the club an awful lot of money but it is something we feel we have to do."