In a large bowl, combine pineapple juice, soy sauce, brown sugar, ketchup, minced garlic, grated ginger, sesame oil, and allspice.
Whisk the marinade ingredients together until the brown sugar is fully dissolved.
Add the chicken thighs to the marinade, making sure they are fully coated.
Cover the bowl and refrigerate for at least 2 hours, or overnight for best results.
Preheat your grill to medium-high heat.
Remove the chicken from the marinade, allowing excess to drip off.
Grill the chicken for 6-8 minutes per side, or until the internal temperature reaches 165°F (74°C).
Let the chicken rest for 5 minutes before serving.