Cech is retiring at the end of the season and he is expected to retain his place in Arsenal's Europa League team for the final against his former club Chelsea in Azerbaijan next week.
However, with Arsenal needing to beat Chelsea to secure a place in next season's Champions League, Seaman believes the 37-year-old should be left out of the starting line-up in Baku in favour of Leno.
Seaman told Sky Sports: “My only thing is that Arsenal really need this; they need this more than Chelsea.
"They need to get into the Champions League and I'm always for playing your strongest team. That means Leno, but I'm sure Cech will play because it's his last ever game."
The former England number one also made it clear that his opinion had nothing to do with the news that Cech was returning to Chelsea, with the Czech expected to take on a behind-the-scenes role at Stamford Bridge.
“I was surprised when I heard it," added Seaman. "I was really surprised at the timing of it. I was thinking, 'is that Chelsea that's brought that out, or someone from Arsenal?'
"Nothing's been confirmed yet, so if Petr plays I wouldn't be worried at all. He's a true professional and even if he is going to join Chelsea, that wouldn't make any difference to his performance."
Over the course of his career, Cech has recorded 317 clean sheets in all competitions, with 202 of those coming in the Premier League, making him the record holder for the most clean sheets in the English top flight’s history.
He has also won the Premier League four times, the FA Cup five times, the League Cup three times, the Community Shield six times, and he has also won both the Europa League and Champions League.
If Cech does feature in the Europa League final, it will be his last ever match as a professional footballer after he announced in January that he is retiring at the end of the season.