Homes for Sale Under 400K in O Fallon, MO

Based on information from Mid America Regional Information Systems, Inc. through Sep 14, 2026, 12:46 PM. All data is obtained from various sources and may not have been verified by broker or MLS GRID. Supplied Open House Information is subject to change without notice. All information should be independently reviewed and verified for accuracy. Properties may or may not be listed by the office/agent presenting the information. Some IDX listings have been excluded from this website. Properties displayed may be listed or sold by various participants in the MLS. Property data presented reflect information otherwise available from public records. The REALTOR® providing this information may not have represented the buyer or seller in some or all of the transactions.
IDX information is provided exclusively for consumers’ personal noncommercial use, that it may not be used for any purpose other than to identify prospective properties consumers may be interested in purchasing, that the data is deemed reliable but is not guaranteed by MLS GRID, and that the use of the MLS GRID Data may be subject to an end user license agreement prescribed by the Member Participant’s applicable MLS if any and as amended from time to time. © 2026 Mid America Regional Information Systems, Inc. All Rights Reserved.