The Swedish striker was in fine form for the Magpies, scoring three times in the last two matches to help Eddie Howe's men record back-to-back wins before the international break.
A brace against Nottingham Forest - including a last-minute winner from the spot - secured three points, with Isak citing the penalty as a personal highlight for him.
"March was a good month for me personally, getting on the scoresheet and helping the team to get important wins," he told nufc.co.uk.
"For me, the late penalty against Nottingham Forest was a big moment. It got us a three points and it was great to score in front of the away fans. It was a special moment."
The March award for Isak was the first time he has claimed the accolade, with the 22-year-old frontman thankful for the support and votes that helped him claim the prize.
"It's always special to get recognised from the supporters and it means a lot," he said. "It means that fans can see that we are all working hard in every game and I'm always grateful for their support and to receive the award for March."
Voting for the FUN88 Player of the Month takes place after every match in the club's post-match email.
To ensure you receive the post-match email - which includes highlights, interviews, stats from the game and more - make sure you have 'news' ticked within preferences in your Newcastle United account. If you don't have an account, you can sign up here.