Three plants operate in the US - all in Texas - with the meat exported mostly to European and Asian markets.
Members of Congress voted 263-146 in favour of the ban.
Opponents of the slaughter trade thought they had victory when legislation was passed last year which stopped the pay of federal meat inspectors at the plants. However, agricultural authorities agreed to a proposal from the plants that they themselves pay the wages, and the trade has continued unabated.
The debate has polarised both Congress and the general community. Opponents have argued the practice is inhumane and barabaric. They maintain it is a terrible fate for animals that played such a key part in the development of the United States.
Supporters have argued that unwanted horses will face potentially years of suffering and neglect if the option of slaughter is removed. It is possible, they argue, the horses may be sent to countries that have less stringent standards.
Nearly 90,000 horses and other equines went to slaughter in the United States last year.
Congress's passing of the bill is the first major step to it becoming law. However, it must now go to the Senate, which must vote in favour of the identical bill. If changes are proposed and passed, the different versions must be reconciled at a conference committee.
Only when Congress and The Senate pass identical bills do they go the President for them to be signed into law.