Doncic was up to his usual tricks for the Mavs as he provided 32 points, nine assists and eight rebounds in his team's dominant display while Irving contributed 25 points of his own as well as eight assists.
Star guard Shai Gilgeous-Alexander gave his all on a tough night for OKC as he dropped 25 points, six rebounds and five assists.
Story of the game
Doncic looked fired up in the opening moments, first netting a contested step back three and then drained another on his next attempt, leaving his defender scrambling following a successful pump fake.
After six minutes, Irving produced a trademark finish with flair at the cup and then assisted Maxi Kleber on the next play to give Dallas a 16 point advantage.
Gafford, who Dallas recently acquired via a trade with Washington, announced his arrival by catching a lob for his first points in his new colours.
Gafford's fellow debutant Washington followed suit moments later with Doncic once again providing the assist to the alley-oop.
Chet Holmgren's corner three brought OKC within 17 of the electric Dallas, who closed out their franchise record first quarter with 47 points.
The Thunder significantly improved in the second and a Holmgren dunk meant they were on a 12-0 run, bringing them within seven points of the Mavericks with just over six minutes until half time.
A minute later an Aaron Wiggins three brought OKC within four of their opponents despite being dominated in the first 12 minutes.
However, Derrick Jones Jr's throw down allowed the Mavericks to establish some distance as they led by 11 with two minutes to go.
Dallas held a comfortable lead heading into the interval with Jason Kidd's side up 62-71 after an entertaining first half.
Josh Green completed an excellent fast break by catching Kleber's lob to give the Mavs a 16 point lead following a great start to the quarter.
Washington netted himself five points in two plays to take his side's points tally up to 100 with 3:39 to play in the third.
Despite his team being 20 points down, SGA continued to hustle, forcing fouls and knocking down tough shots as he closed out the third with 25 points to his name.
With ten seconds left in the quarter, Gafford showed his new city what he is all about as he battled in the paint for a three point play.
Three and a half minutes into the fourth a deep Irving three followed by a Washington floater gave the Texas based side a huge 30 point lead.
Both teams emptied the benches half way through the fourth as OKC's 17th loss of the season was all but confirmed.
The Mavericks closed out the victory and did so by a whopping 35 points with the score reading 111-146.