The 65-year-old said that he watched the Sunderland midfielder while he was at Paris Saint-Germain but did not make a move for the Benin international as his scouts were "not convinced".
"We could have had Sessegnon at one time, I think," London24 quotes Redknapp as saying. "The people who work for me weren't really convinced at the time. They were watching him and they didn't feel that he was any better than what we had, in all honesty.
"Do I regret not taking Sessegnon? Not really. He's a good little player, but I've got Van der Vaart. You're just going to cause yourself a bigger problem."
Redknapp also said that he "probably" could have captured Newcastle United star Hatem Ben Arfa.
"The boy at Newcastle's a good player as well, he's a talent, Ben Arfa," added Redknapp. "He's similar, another good little dribbler. We probably could have had him as well, but you can't take everyone can you? You end up with dozens of players hanging around, and we've got good players here anyway so he might not have got in our team."
Sessegnon moved to Sunderland in last year's January transfer window, while Ben Arfa made his loan switch to Newcastle permanent last summer.