Gospel for Asia is responding after Tropical Storm Mahasen left thousands of people displaced and homeless in Bangladesh and Burma.
The organisation says its initial response will cover a six-month period to help rebuild the homes and lives of those affected.
GFA responders are delivering food and clothing, and establishing temporary shelter.
The organisation says many have "lost everything" and that it will be responding to the disaster "far into 2013".
"There will be months of agony for these suffering people long after the media has forgotten," said KP Yohannan, Gospel for Asia founder and president.
"Rebuilding the lives of those who have lost everything will be the long and difficult task fulfilled by those who remember and remain."
More than a million people were required to evacuate ahead of the storm making landfall last Thursday morning. At least 13 people were killed by the storm.
"These people have lost everything: their goats and chickens, their children's school books, their clothing, their simple livelihood - all has been washed away," said Yohannan. "Fleeing for their lives, they salvaged only what they could carry on their heads or in their arms."
GFA missionaries serving in the area have been trained to counsel in crises and were equipped to respond immediately to the disaster. They will play a pivotal role in GFA's longer-term response.
"In the darkness of these desperate people, we have the opportunity to bring hope and to share the love of Christ through physical help," said Yohannan.
"Hundreds of people far away can respond in prayer and support for those who have lost every earthly possession."