You can determine if a niche is profitable for affiliate marketing with research. You need to check if people search for the niche online. You should use tools like Google Trends or keyword planners. You must find out if the niche has products to promote. You should check affiliate networks for offers in the niche. You need to look at competition in the niche. You should avoid niches with too many competitors. You must see if the niche solves real problems. You should focus on niches people are willing to spend money on. You need to check the commission rates of products. You must pick niches with high earning potential. You should test the niche with small campaigns. You can succeed by staying focused and analyzing results.