diff --git a/ChangeLog.md b/ChangeLog.md
index 3c0e540d..07ea2809 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -99,6 +99,8 @@ repository history](https://github.com/ddclient/ddclient/commits/master).
     [#726](https://github.com/ddclient/ddclient/pull/726)
   * `porkbun`: The update URL hostname is now configurable via the `server`
     option.  [#752](https://github.com/ddclient/ddclient/pull/752)
+  * `ionos`: Added support for updating Ionos records.
+    [#743](https://github.com/ddclient/ddclient/pull/743)
 
 ### Bug fixes
 
diff --git a/Makefile.am b/Makefile.am
index d9baa981..ecf4d230 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -73,6 +73,7 @@ handwritten_tests = \
 	t/protocol_directnic.pl \
 	t/protocol_dnsexit2.pl \
 	t/protocol_dyndns2.pl \
+	t/protocol_ionos.pl \
 	t/read_recap.pl \
 	t/skip.pl \
 	t/ssl-validate.pl \
diff --git a/README.md b/README.md
index 22db4993..2b8a7761 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@ Dynamic DNS services currently supported include:
   * [Hurricane Electric](https://dns.he.net)
   * [Infomaniak](https://faq.infomaniak.com/2376)
   * [INWX](https://www.inwx.com/)
+  * [Ionos](https://ionos.com)
   * [Loopia](https://www.loopia.se)
   * [Mythic Beasts](https://www.mythic-beasts.com/support/api/dnsv2/dynamic-dns)
   * [NameCheap](https://www.namecheap.com)
diff --git a/ddclient.in b/ddclient.in
index 0beb3f88..9d4b9d3c 100755
--- a/ddclient.in
+++ b/ddclient.in
@@ -1295,6 +1295,15 @@ our %protocols = (
             'max-interval' => setv(T_DELAY, 0, 'inf', 0),
         },
     ),
+    'ionos' => ddclient::Protocol->new(
+        'update'     => \&nic_ionos_update,
+        'examples'   => \&nic_ionos_examples,
+        'cfgvars'  => {
+            %{$cfgvars{'protocol-common-defaults'}},
+            'server' => setv(T_FQDNP, 0, 'ipv4.api.hosting.ionos.com', undef),
+            'login' => undef,
+        },
+    ),
 );
 $cfgvars{'merged'} = {
     map({ %{$protocols{$_}{'cfgvars'}} } keys(%protocols)),
@@ -7644,6 +7653,69 @@ Example ${program}.conf file entries:
 EoEXAMPLE
 }
 
+######################################################################
+## nic_ionos_examples
+######################################################################
+sub nic_ionos_examples {
+    my $self = shift;
+    return <<EoEXAMPLE;
+o 'ionos'
+
+The 'ionos' protocol is used by DNS service offered by ionos.com.
+
+Configuration variables applicable to the 'ionos' protocol are:
+  protocol=ionos                ##
+  password=dyndns-update-key    ## the key created to update the host below
+  fully.qualified.host          ## the host registered with the service.
+
+Example ${program}.conf file entries:
+  ## single host update
+  protocol=ionos,
+  password=dyndns-update-key
+  myhost.com
+
+Getting the DynDNS key (only available via Ionos API):
+
+  1. Create an API key
+  2. Enable DynDNS for your host using the /dns/v1/dyndns API
+     (documentation @ https://developer.hosting.ionos.es/docs/dns)
+  3. In the API response, get the key value. The key is a long string
+     from the "q=" parameter. The URL looks like this:
+     https://ipv4.api.hosting.ionos.com/dns/v1/dyndns?q=XXXXXXXXXXXXXXX
+     (in the example above the key is "XXXXXXXXXXXXXXX").
+
+Note: Because the key is individual for each host, you cannot update
+multiple hosts with the same key.
+EoEXAMPLE
+}
+
+######################################################################
+## nic_ionos_update
+## response contains "code 200" on succesfull completion
+######################################################################
+sub nic_ionos_update {
+    my $self = shift;
+    ## update each configured host
+    ## should improve to update in one pass
+    for my $h (@_) {
+        local $_l = pushlogctx($h);
+        my $ip = delete $config{$h}{'wantipv4'};
+        info("setting IP address to $ip");
+        my $url = opt('server', $h) . "/dns/v1/dyndns?q=" . opt('password', $h);
+        my $reply = geturl(proxy => opt('proxy'), url => $url);
+
+        if (header_ok($reply)) {
+            $recap{$h}{'ipv4'} = $ip;
+            $recap{$h}{'mtime'} = $now;
+            $recap{$h}{'status-ipv4'} = 'good';
+            success("IP address set to $ip");
+        } else {
+            $recap{$h}{'status'} = 'failed';
+            failed("server said: $reply");
+        }
+    }
+}
+
 # Execute main() if this file is run as a script or run via PAR (https://metacpan.org/pod/PAR),
 # otherwise do nothing. This "modulino" pattern makes it possible to import this file as a module
 # and test its functions directly; there's no need for test-only command-line arguments or stdout
diff --git a/t/protocol_ionos.pl b/t/protocol_ionos.pl
new file mode 100644
index 00000000..e1f89263
--- /dev/null
+++ b/t/protocol_ionos.pl
@@ -0,0 +1,69 @@
+use Test::More;
+BEGIN { eval { require Test::Warnings; } or skip($@, 1); }
+BEGIN { eval { require 'ddclient'; } or BAIL_OUT($@); }
+BEGIN {
+    eval { require ddclient::t::HTTPD; 1; } or plan(skip_all => $@);
+    ddclient::t::HTTPD->import();
+    plan tests => 2;
+}
+
+{
+    package Logger;
+    use parent qw(-norequire ddclient::Logger);
+    sub new {
+        my ($class, $parent) = @_;
+        my $self = $class->SUPER::new(undef, $parent);
+        $self->{logs} = [];
+        return $self;
+    }
+    sub _log {
+        my ($self, $args) = @_;
+        push(@{$self->{logs}}, $args)
+            if ($args->{label} // '') =~ qr/^(?:WARNING|FATAL|SUCCESS|FAILED)$/;
+        return $self->SUPER::_log($args);
+    }
+}
+
+# Subtest for the protocol_ionos
+subtest 'Testing protocol_ionos' => sub {
+    # Mock HTTP server
+    httpd()->run(sub {
+        my ($req) = @_;
+        diag('==============================================================================');
+        diag("Test server received request:\n" . $req->as_string());
+
+        return undef if $req->uri()->path() eq '/control';
+        return [400, $textplain, ['invalid method: ' . $req->method()]] if $req->method() ne 'GET';
+        return undef
+    });
+
+    local $ddclient::globals{debug} = 1;
+    local $ddclient::globals{verbose} = 1;
+    my $l = Logger->new($ddclient::_l);
+
+    local %ddclient::config = (
+        'host.my.example.com' => {
+            'protocol' => 'ionos',
+            'password' => 'mytestingpassword',
+            'server'   => httpd()->endpoint(),
+            'wantipv4' => '1.2.3.4',
+        },
+    );
+
+    httpd()->reset([200, $textplain, []]);
+
+    {
+        local $ddclient::_l = $l;
+
+        ddclient::nic_ionos_update(undef, 'host.my.example.com');
+    }
+
+    my @requests = httpd()->reset();
+    is(scalar(@requests), 1, "Single update request");
+
+    my $req = shift(@requests);
+    is($req->uri()->path(), '/dns/v1/dyndns', "Correct request path");
+    is($req->uri()->query(), 'q=mytestingpassword', "Correct request query");
+};
+
+done_testing();