The home side managed the victory with a strong first half performance, which saw them take a 28-11 lead at the break, never allowing the Eastern Cape visitors to settle down in a cool, but sunny Welkom.
The Griffons outscored EP five tries to two, reflecting their dominance, especially at scrum time and with a backline that fired on all cylinders. Four of the five tries came via the backs, with winger Gurshwin Wehr getting a brace, while No 8 Soso Xakalashe benefitted from a strong lineout drive.
The visitors scored first via flyhalf Garrick Mattheus, showing that they had come to play. EP managed to stop the early attacks launched by the home side, but once fullback Dommenic Smit sliced through after 10 minutes to score under the poles and hand the Griffons the lead, it was clear that they were in for a real battle.
Scrumhalf Jaywinn Juries converted for a 7-3 score line and extended the lead with a penalty goal 15 minutes in when EP backline strayed offside in a desperate attempt to stop a building Griffons attack.
Matteus reduced that immediately with a long-range effort from just inside the Griffons half sailing through the uprights, but the respite was short-lived.
Another strong forward drive by the home side resulted in another penalty and another three points from Juries for a 13-6 lead.
EP struck just before the half hour mark with a lovely try by Rodney Damons in the corner. The left wing was given some space created by fullback Mbembe Payi joining the line and dotted down with two defenders in close attendance. The conversion was wide, but the hosts' lead was cut to two.
The Griffons responded in fine style. First centre Marquit September broke through and when he was dragged down short of the line, EP hooker Duan du Plessis stopped him from recycling the ball. Du Plessis was sent to the sinbin for his effort and the Griffons kicked for the corner.
Xakalashe scored off the back of a strong Griffons lineout drive and when Juries was on target again with his conversion, the Northern Free Staters' lead was extended again, this time to 20-11.
That soon became 25-11 as Wehr stepped inside and then outside his man for a try in the corner. Juries missed his conversion, but the alarm bells were ringing loud and clear for the visitors.
Juries kicked another long-range penalty to extend the lead to 28-11 at the break.
It became 31-11 in the opening minutes of the second half as Juries slotted another penalty to set the tone for the second half.
Sensing that they needed to get back into the game quickly, EP struck with a well-taken try by Payi, with the fullback regathering a kick ahead and dotting down, but that was the last time they would bother the scorers again.
The Griffons lost wing Granwill Matthys to a yellow card for a high tackle 65 minutes in, but kept the pressure on the visitors.
Juries missed two attempts at goal, but when September dotted down after sustained attack by the Griffons, it was clear that there would only be one winner. Wehr finished the campaign off in style with a run down the touchline and captain and flyhalf Duan Pretorius converted for a perfect ending to a perfect season, with the Griffons finishing undefeated.
Down Touch Griffons 45 (28) - Tries: Dommenic Smit, Soso Xakalashe, Gurshwin Wehr (2), Marquit September. Conversions: Jaywinn Juries (3), Duan Pretorius. Penalty goals: Juries (4).
Eastern Province 16 (11) - Tries: Rodney Damons, Mbembe Payi. Penalty goals: Garrick Mattheus (2).