Coutinho, 25, has been a part of Mumbai FC since 2008. He started his career with the youth team and managed to quickly climb up the ladder and make his mark in the senior team in the 2011-12 season.
Nidhin Lal, with the club since 2011, previously played for Pune FC and Indian Bank, and was also a part of the Kerela team that stood third in the Santosh Trophy in 2012.
"Mumbai FC is very close to my heart. The club has become my family and I am really happy to extend my contract here," said Coutinho.
"Players like John are part of the Mumbai FC philosophy. It's always good to see your youth players rise up the ranks to be part of the senior team."
Heaping praise on Nidhin, the coach said, "His attitude has been fantastic since day one. I believe he has great potential and he'll do well if he continues to work hard the way he does.