Proctor only joined up with his new team-mates on Tuesday after completing a one-month loan move from Championship strugglers Rotherham United, but produced the crucial moment of the game in the 25th minute.
A long ball downfield fell kindly to the former Sunderland striker to produce a clinical finish as he beat Vale goalkeeper Mark Goodlad with a low shot to earn Swindon their fourth win in five games.
Midfielder Sam Igoe had already forced Goodlad to make a good save before Proctor deservedly gave the home side the lead and only further good blocks from the Vale goalkeeper prevented Swindon from going further in front at the interval.
Goodlad moved swiftly to block a 25-yard effort from Grant Smith while he again denied Smith a minute before the interval following an inswinging free-kick on the right.
Vale's best chance of the first half fell to Billy Paynter. However, their leading scorer rushed his shot when unmarked allowing Swindon goalkeeper Rhys Evans to save to his right in the 43rd minute.
Paynter did much better with a diving header on the run four minutes after the re-start but Evans somehow tipped his six-yard effort over the crossbar.
Proctor went close to grabbing his second goal ten minutes before the final whistle when his left-footed shot again found Goodlad in the way and the visitors had a chance to equalise with five minutes remaining through Michael Cummins.
Cummins found himself with a clear sight on goal just ten yards out and struck his shot cleanly but his effort fell straight into the arms of Evans and the home side clung on for the three points.