The 21-year-old has already been training with the SPL side and is expected to sign for the rest of the season when the transfer window opens on January 1.
Lennon has yet to see Newton play a game, but revealed he could tell the midfielder had quality just from watching train and is convinced he will have a big impact on St Mirren's campaign.
He said: "I remember when I signed Jeroen Tesselaar, we took him away to Portugal with us. I knew without seeing him in a game that he would come in and do well for us.
"[It is the] same with Conor. He is technically sound, a good passer and has a hunger and desire. He has everything that we look for in a player. I am very confident he will come in and make a massive contribution."
Lennon hopes to have Newton available for St Mirren's first match of the new year on Wednesday - and refused to rule out making the deal permanent should he impress.
He added: "We have had good dialogue with Newcastle and I expect that one to go down prior to the Kilmarnock game next week.
"It would be a loan until the end of the season. We would monitor his progress and see where that takes us, but he is still a Newcastle player at this moment in time."
He added: "We have certainly enjoyed what we have seen over the last two or three weeks. He has fitted into the group. He will give the group a helping hand, which is something we need.
"I have no idea what Conor's thoughts are on whether or not he sees his future at Newcastle, but we are just delighted to get him for six months. If he is happy at the end of that and talks open up, we will see what his thoughts are."
Lennon also revealed he is in negotiations to sign 22-year-old Sporting Kansas City striker Dom Dwyer on loan.
He said: "We are in talks, but at the moment they have not come back to us, so we are in limbo."