Conan O'Brien is looking forward to his return to "The Tonight Show" 14 years after his messy exit ... telling TMZ there's no bad blood, and that he's excited to hit the stage again.

We caught up with the comedian outside the Whitby Hotel in NYC Tuesday -- just as he was on his way to film his 'TS' appearance at 30 Rock -- where he told us how he was feeling heading into his highly-anticipated late-night comeback.

As Conan puts it ... he's jazzed to be in front of the camera again in that environment -- as he has nothing but fond memories about his time there, which is interesting considering he was fired by NBC in 2010 ... and rather unceremoniously too.

COB says the 'Tonight Show' was a big part of his life ... and he's a fan of Jimmy Fallon, so he's looking forward to the guest spot -- where he'll be plugging his new travelogue series.

In terms of whether he jumped at the opportunity ... Conan says hell yeah, as he says he needed the work.

Remember, Conan gave up his longtime 'Late Night' gig in 2009 to host NBC's beloved evening talk show ... but he was only on the job for 7 months before the execs at the time gave him the boot, making way for Jay Leno's grand return in 2010. After his exit, Conan launched a new late-night show on TBS, which ran for 11 seasons.

And, as you well may know, Jimmy stepped in to Jay's hosting shoes in 2014 ... leading the charge on "The Tonight Show" ever since. So, Conan coming back is a major deal -- especially considering how they did him (dirty) back in the day.

And yet, despite all that ... the dude seemed real chipper talking to us about it -- and he even gave us some insight into how he thinks the current late-night guys are doing.

Long story short ... he thinks they're all talented, and even if late-night talk shows come to an end in the near future -- he believes they'll all land on their feet and be just fine.

Can't wait to see the show!