Millions of low-income children in the United States reside in substandard or unaffordable housing. Relieving these burdens may be associated with changes in asthma outcomes. To examine whether participation in the US Department of Housing and Urban Development's (HUD) rental assistance programs is associated with childhood asthma outcomes and to examine whether associations varied by program type (public housing, multifamily housing, or housing choice vouchers). This survey study used data from the nationally representative National Health Interview Survey linked to administrative housing assistance records from January 1, 1999, to December 31, 2014. A total of 2992 children aged 0 to 17 years who were currently receiving rental assistance or would enter a rental assistance program within 2 years of survey interview were included. Data analysis was performed from January 15, 2018, to August 31, 2019. Participation in rental assistance provided by HUD. Ever been diagnosed with asthma, 12-month history of asthma attack, and 12-month history of visiting an emergency department for the treatment of asthma among program participants vs those waiting to enter a program. Overall participation was examined, and participation in public or multifamily housing was compared with participation in housing choice vouchers. This study included 2992 children who were currently participating in a HUD program or would enter a program within 2 years. Among children with an asthma attack in the past year, participation in a rental assistance program was associated with a reduced use of emergency departments for asthma of 18.2 percentage points (95% CI, -29.7 to -6.6 percentage points). Associations were only found after entrance into a program, suggesting that they were not confounded by time-varying factors. Statistically significant results were found for participation in public or multifamily housing (percentage point change, -36.6; 95% CI, -54.8 to -18.4) but not housing choice vouchers (percentage point change, -7.2; 95% CI, -24.6 to 10.3). No statistically significant evidence of changes in asthma attacks was found (percentage point change, -2.7; 95% CI, -12.3 to 7.0 percentage points). Results for asthma diagnosis were smaller and only significant at the 10% level (-4.3; 95% CI, -8.8 to 0.2 percentage points). Among children with a recent asthma attack, rental assistance was associated with less emergency department use. These results may have important implications for the well-being of low-income families and health care system costs.