The Aberdeen front man joined Saints on a six-month loan deal on Thursday but Lennon thinks the duo can well work as a pair.
And the Buddies boss is confident the 23-year-old Northern Ireland international will take the burden of scoring from the shoulders of his new 35-year-old partner.
Magennis made just one start for the Dons this season but will go straight into the St Mirren squad as they face Scottish Premiership leaders Celtic at Parkhead on Sunday.
Lennon said: “There is no doubt that Josh will help Stevie the longer we go into the season.
“We didn’t bring Josh in as a replacement for Stevie, we brought him in to work alongside him. Stevie is getting older but Josh will be able to do a bit more of the running and help Stevie save himself for when those balls come into the box.
“We have still got Stephane Bahoken, who is just a week away from fitness, as well as Gregg Wylde and Adam Campbell to give us a bit of pace, so our attacking options certainly excite me.”