Shane Horgan scored his 63rd and 64th career tries in a man-of-the-match display at the RDS, which also marked the Boyne man's 190th Leinster appearance.
Isaac Boss touched down for his second try in 10 appearances to date, while Shaun Berne continued his comeback from an Achilles injury with a 75-minute shift in which he too scored a try.
The team and replacements to face the Ospreys is expected to be announced on Friday afternoon.
Speaking ahead of Sunday's game, Leinster head coach Joe Schmidt said that the squad are determined to build on their recent good run of results against a strong Ospreys side.
"We're expecting an even tougher test this weekend. They got a win against Connacht in the last minute which was obviously a pretty good performance considering Connacht weren't too far from (being) full strength," he said.
"They've got some real talent in their young guys whom they have recently given game time in the LV= Cup so they might add something that we don't know so much about.
"We had a few bumps and bruises (out of the victory over the Dragons), but that is pretty much it and we're hopeful that those guys will be available at the end of the week.
"We have a nine-day turnaround so we've got enough time to get anyone with bumps and bruises back on their feet."
Schmidt added: "The last few wins are not just about (being good for) confidence. It's about points on the table.
"Ulster went away and got a really good win against Cardiff and that allowed them to stay in front of us. The Ospreys got their win in Connacht.
"So if you're not winning, then you're going to be very quickly behind the eight-ball and chasing. We want to try and get some kind of established break and make it into the top four."