At least 14 people -- most of them first responders -- died in the April 17 explosion at the West Fertilizer Co. facility 20 miles north of Waco and 70 miles south of Dallas.
At least 200 others were injured, and the estimated insured damage is $100 million.
"West is just a few miles from my hometown of Abbott," Nelson said in a statement. "I was born and raised here and it was my back yard growing up.
"This is my community. These friends and neighbors have always been and are still a part of my life," he said. "My heart is praying for the community that we call home."
Proceeds from Sunday's Willie Nelson and Family Show at The Backyard outdoor amphitheater in Bee Cave will be donated to the West Fire Department, he said.
The concert originally was to celebrate The Backyard's 20th anniversary and Nelson's 80th birthday, Tuesday.
Nelson -- one of the main figures of outlaw country -- has spearheaded fundraisers including 1985's Farm Aid to help and increase awareness of the importance of family farming.
Ten days after the Sept. 11, 2001, terrorist attacks he participated in the benefit telethon "America: A Tribute to Heroes," leading the rest of the celebrities singing the song "America the Beautiful."
Sunday's concert is expected to be attended by firefighters, The Backyard said.