Mahrez found the back of the net with a low drive in the 87th minute which took his tally to 50 goals in the English top-flight as City sealed a 4-1 win over their hosts on Tuesday.
The Algeria international became the ninth African player to hit the milestone, having scored 39 goals at Leicester City and 11 goals for the Etihad Stadium outfit in a total of 177 league appearances.
At the end of the game, Mahrez who has now scored four goals in 11 league games this season, took to social media to celebrate his feat and the victory.
"We are City, happy to reach 50 goals in the Premier League and be the first Algerian to do so," Mahrez wrote on Instagram.
Tuesday's victory at Turf Moor moved Manchester City to second in the league standings, level on points with third-place Leicester City while they are eight points behind leaders Liverpool.
Their next fixture is the Manchester derby against city rivals Manchester United at the Etihad Stadium on Sunday.