Sandow landed a difficult conversion of Hayne's second try from out wide to put the Eels ahead 12-10 for the first time in the match and a converted try to Tepai Moeroa sealed the win three minutes later.
"It's great to win like that, we didn't give up," Hayne told host broadcaster Fox Sports post-game.
"I'm not really concerned about how I am going, I just want to win games for the team."
The win pushes the Eels into the top eight to keeps their finals hopes well and truly alive.
The result was a tough one for the Raiders who bounced back strongly from their woeful 54-18 loss to the Warriors.
With Edrick Lee and Jack Wighton back, Canberra opened the scoring in the 11th minute when Bill Tupou crossed on their right flank courtesy of a nice ball from Josh McCrone.
In a first half arm-wrestle Lee was instrumental in Jarrod Croker's 17th minute try when he handed back a McCrone kick for the Raiders to lead 10-0.
Semi Radradra then bullocked his way down Parramatta's left side before dishing off to Hayne who ran 20m to open the Eels account in the humid conditions before 9,527 fans.
In his first game since 2008, Raiders fullback Jordan Rapana had a mixed night at the back and Anthony Milford was likewise at five-eighth for the Raiders who sit at the foot of the NRL ladder, ahead of just Cronulla on for and against.
Eels forward Junior Paulo was put on report for a dangerous tackle on Brett White in the 67th minute.
- AAP