Blaney finished sixth and scored eight stage points in a race narrowly won by Kyle Larson from Christopher Bell, but the Team Penske driver was later disqualified when his #12 Ford Mustang failed post-race inspection.
The reason behind the initial disqualification was for violating NASCAR Rule Book section 14.11.3.5, which lists the minimum extended damper lengths for each shock.
The sole remaining Penske driver in championship contention, Blaney was 56 points below the cut-line in the playoffs after being disqualified, but is now back to just 17 points out after having his original finish reinstated. He jumps back ahead of fellow Ford driver Chris Buescher and now sits seventh among the eight remaining title contenders.
The Talladega winner faced the scenario of needing to win either of the two remaining Round of 8 races at Homestead and Martinsville to secure a berth in the Championship 4 race at Phoenix.
A statement from NASCAR said: “After further review of the inspection process throughout this weekend’s events at Las Vegas Motor Speedway, NASCAR has rescinded the No. 12 disqualification penalty.
"Monday morning during its race weekend debrief, NASCAR discovered an issue with the damper template used for inspection.
"NASCAR then conducted a detailed investigation, and has restored the #12’s stage and race finishing positions from Sunday.
"NASCAR has taken internal steps to remedy this issue moving forward.”
Larson locked himself into the Championship 4 by winning at Las Vegas, with two races to go for the remaining seven drivers to ensure they join him.
Behind Larson, William Byron is nine points clear of Bell in fifth, with Martin Truex Jr. and Denny Hamlin provisionally also in, albeit that pair only two points ahead of Bell.
Tyler Reddick is 16 points shy of Truex and Hamlin, with Blaney 17 points down and Buescher 23 points adrift.
In response to Blaney's reinstatement, a Team Penske statement said: "We are pleased with the decision by NASCAR to rescind the post-race disqualification to the No. 12 car following Sunday's race at Las Vegas Motor Speedway.
"NASCAR has shown a tremendous amount of integrity throughout the process which has led to this conclusion.
"We are proud of the effort and the results by the No. 12 team during the 2023 season. We look forward to continuing the pursuit of the NASCAR Cup Series championship."
