This study examined the communication techniques of the Rivers State Waste Management Agency (RIWAMA) in promoting environmental awareness and behavioral change among residents of Port Harcourt. Anchored on Development Media Theory and Diffusion of Innovation Theory, it explored how communication drives community participation in waste management. The study adopted a mixed-method design, combining a survey of 384 residents with in-depth interviews involving four RIWAMA officials. Data were analyzed using simple percentages, Weighted Mean Scores, and Constant Comparative Technique (CCT). Findings revealed that RIWAMA’s communication techniques are moderately effective but lack adequate clarity and audience segmentation. Awareness levels are relatively high yet uneven across communities, with weak behavioral compliance. Radio and television remain dominant channels, while interpersonal and social media outreach are underutilized. Residents’ responses to campaigns are positive but shortlived, and campaign frequency is inconsistent. The study recommends enhanced audience targeting, participatory communication, and consistent community engagement to ensure sustained environmental responsibility and effective waste management.