Gather all ingredients.
Mix together canola oil, lemongrass, lemon juice, soy sauce, brown sugar, garlic, and fish sauce in a glass bowl until sugar is dissolved
Add chicken and turn to coat in marinade. Marinate chicken in the refrigerator for 20 minutes to 1 hour.
Preheat grill for medium heat and lightly oil the grate. Remove chicken thighs from marinade; shake to remove excess. Discard remaining marinade.
Cook chicken on the preheated grill until no longer pink in the center and juices run clear, 3 to 5 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
