WhatsApp now reaches 3.3 billion monthly active users as of January 2026, a milestone the platform hit while still adding roughly a billion users every five years (Backlinko WhatsApp User Statistics, 2026). For affiliate marketers, that's a bigger audience than email, SMS, and most ad platforms combined. So why are most affiliates still ignoring it? The answer involves Meta's strict commerce policy, opaque approval processes, and a pricing model that punishes mistakes. This guide walks through the strategy, compliance reality, and scaling playbook for running affiliate offers on WhatsApp in 2026, drawing on conversations with operators across Tier 1, 2, and 3 markets.