Cross-selling, in sales, is when a customer is persuaded to add an additional, complementary product to their purchase. Cross-selling is important because it boosts overall revenue and can also increase the customer's satisfaction since the related product serves to improve their experience with the product initially being purchased as well.

The key to cross-selling is o understand the customer's needs and anticipate a product that would help improve their experience with that product or service. Cross-selling is not effective and can lead to dissatisfaction is the complementary product is irrelevant, inappropriate or incompatible.

Cross-selling is similar to upselling, which is when a salesperson persuades a customer who is already making a purchase to opt for a more premium option.

An example of cross-selling in B2B SaaS would be a company that sells their CRM to a customer also marketing a document-management technology that would help support the function of that customer's business.