In a large saucepan, melt the butter over medium-high heat and sauté the onion, celery, and bell pepper until soft, about 5 minutes.
Add the garlic and cook for an additional minute or two.
Stir in the cans of cream of mushroom soup and the cans of cream of celery soup and mix until combined.
Add the Rotel tomatoes and stir to combine, then reduce heat to low and let simmer for 10 minutes.
Add in crawfish tails and let cook for an additional 20-30 minutes, stirring occasionally so that the sauce does not stick or burn.
Serve over cooked white rice.