Edin Dzeko struck after 14 minutes to bring up the milestone and further goals from Jesus Navas, Yaya Toure and Sergio Aguero finished off Ole Gunnar Solskjaer's plucky Cardiff side to keep ruthless City breathing down the necks of leaders Arsenal.
City, who have won all of their 11 home league games so far this season, are the first team in England to reach 100 goals in all competitions before the end of January with their total now standing at 103 and counting.
"I think it's very important for the team, it's not easy to score 100 goals at this stage of the season," manager Manuel Pellegrini told the club's website (www.mcfc.co.uk)
"It reflects how we think this team must play - we must be confident in what we are doing.
"I think we are getting better as the season goes on."
City have scored 68 goals in all competitions in front of their home fans and now have 63 in 22 league games, 40 behind Chelsea's 2009-10 Premier League record with 16 matches left.
Aston Villa hold the record for most goals in a domestic top flight league campaign with 128 in 42 games in 1930-31.
While scoring records are welcome, Pellegrini is more concerned with churning out victories.
Saturday saw City chalk up a seventh successive league win and they look unstoppable, especially at home.
"We have to play 16 more games, so we have a lot of points to fight for, we are not worried about what happens with other teams," added Pellegrini.
"We are in a good moment - the confidence of the whole squad is high. In the last month (of the season) we will be under a lot of pressure and I hope we'll continue in this way."