<?xml version="1.0" encoding="us-ascii"?>
<!-- DFIN - https://www.dfinsolutions.com/ -->
<!-- CTU Version: Release master Build:20210621.2 -->
<!-- Creation date: 6/23/2021 3:40:40 PM Eastern Time -->
<!-- Copyright (c) 2021 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema
  xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric"
  xmlns:num="http://www.xbrl.org/dtr/type/numeric"
  xmlns:us-types="http://fasb.org/us-types/2020-01-31"
  xmlns:fmnb="http://www.farmersbankgroup.com/20210622"
  xmlns:dei="http://xbrl.sec.gov/dei/2020-01-31"
  xmlns:xbrli="http://www.xbrl.org/2003/instance"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xbrldt="http://xbrl.org/2005/xbrldt"

  attributeFormDefault="unqualified"
  elementFormDefault="qualified"
  targetNamespace="http://www.farmersbankgroup.com/20210622"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance" />
    <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase" />
    <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd" namespace="http://xbrl.sec.gov/dei/2020-01-31" />
    <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/numeric" />
    <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/non-numeric" />

    <xsd:import schemaLocation="https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd" namespace="http://xbrl.sec.gov/naics/2017-01-31" />
    <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt" />
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fmnb-20210622_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Label Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="fmnb-20210622_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation Links, all" xlink:type="simple" />
      <link:roleType roleURI="http://www.farmersbankgroup.com//20210622/taxonomy/role/DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
</xsd:schema>
