The shot-stopper - who spent two seasons at Carrow Road - is aware him and his team-mates must kick on after falling to 17th in the Premier Leage standings
The Welsh side are keen to reverse a form slump which has them slide to 17th in the Premier League table.
Norwich are just a point behind them in 18th and Marshall knows matches against fellow strugglers will be vital in Cardiff's survival bid this season.
The Scotland international told WalesOnline: "It's a significant match for me against a club I played for.
"But it's huge for us as a whole. It's important we do well against teams around us."
Malky Mackay's team have made a mixed start to life in the Premier League, with their win over Manchester City followed by just one more.
Cardiff lost 4-1 at Chelsea in their last Premier League fixture on Saturday.