कटाई या 'कटनी' (harvesting) वह कृषिकार्य है जिसमें तैयार फसल को खेतों से काटकर एकत्रित किया जाता है। इसके बाद उसकी मड़ाई, ओसौनी एवं भण्डारण किया जाता है।

Harvesting is the process of collecting plants, animals, or fish as food, especially the process of gathering mature crops, and "the harvest" also refers to the collected crops. Reaping is the cutting of grain or pulses for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-intensive activity of the growing season. On large mechanized farms, harvesting uses farm machinery, such as the combine harvester. Automation has increased the efficiency of both the seeding and harvesting processes. Specialized harvesting equipment, using conveyor belts for gentle gripping and mass transport, replaces the manual task of removing each seedling by hand. The term "harvesting" in general usage may include immediate postharvest handling, including cleaning, sorting, packing, and cooling.