The black, green and gold provided plenty of thrills on the final day of the regular season at cinch Stadium at Franklin's Gardens, scoring 10 tries.
Falcons had their moments as they pulled back from 36-7 down at half-time to 36-26 behind during the early stages of the second half.
But Saints stopped the nerves jangling too much as they took control again, helped by a red card for Falcons lock Sean Robinson, who made head on head contact with Dan Biggar.
Saints will now look forward to a trip to local rivals Leicester Tigers in the Premiership play-offs next Saturday.
Chris Boyd's side had gone into the game against Falcons knowing a win would be enough to set up a knockout clash.
And Saints were ahead inside four minutes as Fraser Dingwall and Sam Matavesi trapped Joel Hodgson, winning a breakdown penalty that Biggar slotted with ease.
Matavesi was soon involved again as Matias Orlando threw a loose pass and the ball bounced loose, allowing the Saints hooker to kick ahead first time before gathering to score.
Biggar missed the conversion in windy conditions and Falcons soon had a couple of chances to apply some pressure in the home 22, but they couldn't find a way through.
And Saints were looking ruthless at the other end as Biggar and Dingwall combined to set Alex Coles free for a second Saints try.
Biggar added the extras and it was 15-0 with 20 minutes gone.
Saints lost Paul Hill to concussion as he failed his head injury assessment, but the hosts soon had score number three as Matavesi broke from a lineout drive to grab his second try.
Biggar converted, but Falcons responded with a tidy try of their own as Callum Chick ran a fine line, flew forward and sidestepped George Furbank before scoring.
Hodgson converted and it was made clear to Saints that the job was far from done 10 minutes before the break.
The sun soon appeared for the first time and Saints flicked the switch to summer rugby with a lovely score.
Matavesi flew forward before Api Ratuniyarawa did likewise, offloading to Coles, who gave the ball to Alex Mitchell for the bonus-point try.
Newcastle almost hit back soon after but some strong defending on their own line allowed Saints to relieve the pressure.
But the reprieve was only temporary as the lineout was overthrown, allowing the Falcons to push on and earn another penalty.
However, Falcons were undone by Greg Peterson as the lock landed an uppercut on Lewis Ludlam, costing his side a penalty and earning him a yellow card.
And there was still time for Saints to mount one final attack before the break as Rory Hutchinson weaved his way through before the ball was sent left with some lovely handling for Freeman to score.
Biggar added the conversion with the final kick of the half to take the lead to 36-7 as the hosts were applauded from the field.
But Saints didn't have a smooth start to the second half and they allowed the 14-man Falcons to secure a lifeline.
Mitchell was sin-binned for coming in at the side to tackle George McGuigan into touch, prompting referee Karl Dickson to also award a penalty try in the process.
It came at a time when Falcons were just preparing to welcome Peterson back to the field, meaning the roles were reversed with 14-man Saints up against 15-man Newcastle.
The hosts were struggling to get any momentum in the game after the interval and Falcons soon scored again.
The away side's lineout drive had caused problems, and it paid dividends when replacement hooker Jamie Blamire grabbed his side's third score.
Hodgson couldn't convert but nerves were just starting to jangle as Saints sought a spark.
But it was one-way traffic and Newcastle pieced together a superb move that ended with Adam Radwan scoring in the corner.
Saints needed to summon a response and it was Juarno Augustus who lit the fuse with a big carry before Hutchinson scored in the corner.
The TMO was called on to look at an incident in the build-up and Falcons lock Robinson was red carded for a head to head hit on Biggar.
Saints were up and running again now though, and they scored another from a rapid counter-attack.
Manny Iyogun did brilliantly to strip the ball on his own line and Saints flew forward, with Freeman turning on the turbos to cruise in from halfway.
Saints thought they'd scored again soon after but Augustus had a foot in touch when he flew over in the corner.
But the hosts didn't have to wait much longer for another five-pointer as Falcons lost the ball on the break and Freeman kicked ahead before chasing it to complete his hat-trick.
Biggar again missed the conversion but Saints had a half-century of points and they were sauntering into the play-offs.
There was still time for another eye-catching Saints try as Augustus booted the ball towards halfway and Courtnall Skosan raced forward, putting boot to ball before pouncing when the ball rebounded off the right post.
Biggar converted and some Saints fans started singing 'if you're happy and you know it clap your hands'.
And they were even happier and clapping even more soon after as Biggar landed a crossfield kick in the hands of Skosan, who gave it to Ludlam, and the skipper finished in fine fashion to crown his 100th Saints appearance in style.
Biggar landed the conversion with the final kick of the match and a roar went up as the victory, and safe passage into the play-offs, was confirmed.
Saints: Furbank; Proctor, Dingwall (James 52), Hutchinson, Freeman; Biggar, Mitchell (Skosan 58); Waller (Iyogun 58), Matavesi (Haywood 58), Hill (Painter 22); Coles (Nansen 66), Ratuniyarawa; Lawes, Hinkley (Augustus 58), Ludlam (c).
Newcastle Falcons: Tait; Radwan, Orlando (Haydon-Wood 58), Burrell (Wacokecoke 48), Carreras; Hodgson, Nordli-Kelemeti (Blackett 75); Brocklebank (Mulipola 48), McGuigan (Blamire 52), Davison (Kenny 58); Peterson, Robinson; Graham (Fearns 48), Basham, Chick (c).
Referee: Karl Dickson