<p>This study investigated the caffeine content in a variety of beverages and chocolate products using a rapid and straightforward method. High-performance thin-layer chromatography (HPTLC) combined with densitometric analysis was employed for efficient separation and quantification. The separation was performed on HPTLC silica gel F₂₅₄ plates developed with ethyl acetate‒methanol‒water (20:2.7:2, <i>V/V</i>) in a horizontal developing chamber that allowed analyses of up to 40 samples simultaneously. Quantification was performed on the basis of the peak areas obtained by densitometric scanning at 275 nm in absorption/reflectance mode. The calibration range was from 10 to 150 ng. The evaluation of caffeine content in coffee, tea (black, green, and white), hot chocolate, cacao, carbonated soft drinks, and energy drinks was on the basis of the caffeine content in 100 mL of beverages as well as caffeine content per serving. Similarly, the caffeine content per 100 g of chocolate (milk and dark—45%, 70%, and 75%) was compared, and the results were compared with the caffeine content in “baking chocolate standard reference material SRM 2384.” In beverages, the caffeine content per 100 mL ranged from: ~2 mg to ~6 mg in cocoa and hot chocolate, ~9 mg to ~12 mg in soft drinks, ~10 mg to ~24 mg in teas, ~29 mg to ~33 mg in energy drinks, and ~69 mg to ~252 mg in coffees. In chocolates, the caffeine contents in 100 g ranged from ~12 mg in milk chocolate to ~54 mg in 75% dark chocolate, while the “baking chocolate standard reference material SRM 2384” contained ~100 mg of caffeine. The highest caffeine content per serving was determined in coffee brewed from ground coffee beans using a domestic recipe. This was followed by three types of coffee from vending machines, while energy drinks ranked only fifth and sixth in terms of caffeine content.</p>