Hibs took the lead in the 27th minute through Christian Doidge but were penned in for long spells of the second half as St Mirren sought an equaliser.
Ross said: “It was all about winning the game.
“We had to dig it out. It’s still early but it’s given us a platform to push on.”
“Sometimes you’ve just got to find a way to win the game – and we’ve done that tonight,” added the former St Mirren boss on his return to Paisley.
Stevie Mallan got Hibs’ second from the penalty spot after a breakaway, meaning Junior Morias’ last gasp goal was mere consolation
St Mirren manager Jim Goodwin said: “We’re extremely disappointed but I couldn’t be more proud of the players in terms of their effort and commitment in the second half.
“It wasn’t just their effort but some of the football that they played. It’s a long, long time since one of my sides dominated a half of football like that against a very good team. But unfortunately we’ve nothing to show for it.”