Rousey looked to be in control after hitting Piper's Pit, but Lynch immediately turned the tables. She got the former UFC star's shoulders on the mat for the three-count.
The loss marked Rousey's first in a non-tag team match in WWE, while The Man became Raw women's champion for the first time and the SmackDown women's champion for the third time.
Lynch's road to the top of the women's division was a long and winding one that began at the Royal Rumble on Jan. 27.
After losing a SmackDown Women's Championship match to Asuka earlier in the night, she replaced an injured Lana in the Rumble match and last eliminated Charlotte to win and earn a title shot at WrestleMania.
The Man immediately set her sights on Rousey since their scheduled match at Survivor Series in November never took place due to Lynch suffering a legitimate concussion and broken face at the hands of Nia Jax.
Lynch's road to WrestleMania became far more complicated after that, though, as Stephanie McMahon and Triple H suspended her. The Irish Lass Kicker refused to get her knee checked after injuring it during the Rumble match, so the WWE executives would not allow her to compete.
After making several uninvited appearances on Raw and SmackDown, Lynch finally agreed to get her knee looked at, and she was ultimately cleared. However, another wrench was thrown into her plans when Vince McMahon suspended her because he disliked her attitude and gave Charlotte the WrestleMania title shot instead.
Lynch then proceeded to make life miserable for Rousey and Charlotte to the point that she attacked them on multiple occasions. Rowdy wanted to get her hands on The Man so badly that she laid down the Raw women's title when Stephanie refused to add her to the match.
Stephanie took that as Rousey vacating the title, so she reinstated Lynch and booked a Raw Women's Championship match between The Man and Charlotte at Fastlane on March 10.
Rousey clarified that she did not give up the title, though, which led to Stephanie instead giving Lynch vs. Flair the stipulation of The Man getting added to the WrestleMania match if she could beat The Queen.
Lynch did beat Charlotte by disqualification when Rousey interfered, so the Raw Women's Championship match at WrestleMania 35 officially became a Triple Threat.
Another wrinkle was added to the match in the weeks prior to WrestleMania when Rousey turned heel and seemingly became even more dangerous than she was previously. With both her and Flair working as heels, Lynch was the clear sentimental fan favorite.
Additionally, Charlotte beat Asuka for the SmackDown women's title before WrestleMania, which resulted in a winner-takes-all title match on The Grandest Stage of Them All.
Seemingly the entire live crowd at MetLife Stadium in East Rutherford, New Jersey, was behind Lynch, and when she finally scored the victory, the deafening reaction validated everything she has done in recent months.
With Lynch now having the titles to back up her strong words, the question becomes whether Rousey will stick around in an attempt to regain the championship she held for nearly eight months.
Listen to Ring Rust Radio for all of the hot wrestling topics. Catch the latest episode in the player below (warning: some language NSFW).