diff --git a/pkg/cmd/auth/shared/login_flow.go b/pkg/cmd/auth/shared/login_flow.go
index 837ff0d64..4f2cb9e0c 100644
--- a/pkg/cmd/auth/shared/login_flow.go
+++ b/pkg/cmd/auth/shared/login_flow.go
@@ -200,7 +200,7 @@ func Login(opts *LoginOptions) error {
 	}
 
 	if keyToUpload != "" {
-		err := sshKeyUpload(httpClient, hostname, keyToUpload, keyTitle)
+		err := sshKeyUpload(httpClient, hostname, keyToUpload, keyTitle, opts.IO)
 		if err != nil {
 			return err
 		}
@@ -223,14 +223,14 @@ func scopesSentence(scopes []string, isEnterprise bool) string {
 	return strings.Join(quoted, ", ")
 }
 
-func sshKeyUpload(httpClient *http.Client, hostname, keyFile string, title string) error {
+func sshKeyUpload(httpClient *http.Client, hostname, keyFile string, title string, ios *iostreams.IOStreams) error {
 	f, err := os.Open(keyFile)
 	if err != nil {
 		return err
 	}
 	defer f.Close()
 
-	return add.SSHKeyUpload(httpClient, hostname, f, title)
+	return add.SSHKeyUpload(httpClient, hostname, f, title, false, ios)
 }
 
 func getCurrentLogin(httpClient httpClient, hostname, authToken string) (string, error) {
diff --git a/pkg/cmd/auth/shared/login_flow_test.go b/pkg/cmd/auth/shared/login_flow_test.go
index f01ba46ff..92ae75915 100644
--- a/pkg/cmd/auth/shared/login_flow_test.go
+++ b/pkg/cmd/auth/shared/login_flow_test.go
@@ -38,6 +38,9 @@ func TestLogin_ssh(t *testing.T) {
 	tr.Register(
 		httpmock.GraphQL(`query UserCurrent\b`),
 		httpmock.StringResponse(`{"data":{"viewer":{ "login": "monalisa" }}}`))
+	tr.Register(
+		httpmock.REST("GET", "api/v3/user/keys"),
+		httpmock.StringResponse(`[]`))
 	tr.Register(
 		httpmock.REST("POST", "api/v3/user/keys"),
 		httpmock.StringResponse(`{}`))
@@ -78,7 +81,7 @@ func TestLogin_ssh(t *testing.T) {
 		}
 		assert.Equal(t, expected, args)
 		// simulate that the public key file has been generated
-		_ = os.WriteFile(keyFile+".pub", []byte("PUBKEY"), 0600)
+		_ = os.WriteFile(keyFile+".pub", []byte("PUBKEY asdf"), 0600)
 	})
 
 	cfg := tinyConfig{}
diff --git a/pkg/cmd/ssh-key/add/add.go b/pkg/cmd/ssh-key/add/add.go
index e3f5088d2..df977b291 100644
--- a/pkg/cmd/ssh-key/add/add.go
+++ b/pkg/cmd/ssh-key/add/add.go
@@ -1,7 +1,6 @@
 package add
 
 import (
-	"fmt"
 	"io"
 	"net/http"
 	"os"
@@ -79,14 +78,11 @@ func runAdd(opts *AddOptions) error {
 
 	hostname, _ := cfg.Authentication().DefaultHost()
 
-	err = SSHKeyUpload(httpClient, hostname, keyReader, opts.Title)
+	err = SSHKeyUpload(httpClient, hostname, keyReader, opts.Title, true, opts.IO)
 	if err != nil {
 		return err
 	}
 
-	if opts.IO.IsStdoutTTY() {
-		cs := opts.IO.ColorScheme()
-		fmt.Fprintf(opts.IO.ErrOut, "%s Public key added to your account\n", cs.SuccessIcon())
-	}
+	// SSHKeyUpload prints the success message.
 	return nil
 }
diff --git a/pkg/cmd/ssh-key/add/add_test.go b/pkg/cmd/ssh-key/add/add_test.go
index 565528ddd..8497dc991 100644
--- a/pkg/cmd/ssh-key/add/add_test.go
+++ b/pkg/cmd/ssh-key/add/add_test.go
@@ -11,33 +11,94 @@ import (
 )
 
 func Test_runAdd(t *testing.T) {
-	ios, stdin, stdout, stderr := iostreams.Test()
-	ios.SetStdinTTY(false)
-	ios.SetStdoutTTY(true)
-	ios.SetStderrTTY(true)
+	tests := []struct {
+		name       string
+		stdin      string
+		opts       AddOptions
+		httpStubs  func(*httpmock.Registry)
+		wantStdout string
+		wantStderr string
+		wantErrMsg string
+	}{
+		{
+			name:  "valid key format, not already in use",
+			stdin: "ssh-ed25519 asdf",
+			httpStubs: func(reg *httpmock.Registry) {
+				reg.Register(
+					httpmock.REST("GET", "user/keys"),
+					httpmock.StringResponse("[]"))
+				reg.Register(
+					httpmock.REST("POST", "user/keys"),
+					httpmock.RESTPayload(200, ``, func(payload map[string]interface{}) {
+						assert.Contains(t, payload, "key")
+						assert.Empty(t, payload["title"])
+					}))
+			},
+			wantStdout: "",
+			wantStderr: "✓ Public key added to your account\n",
+			wantErrMsg: "",
+			opts:       AddOptions{KeyFile: "-"},
+		},
+		{
+			name:  "valid key format, already in use",
+			stdin: "ssh-ed25519 asdf title",
+			httpStubs: func(reg *httpmock.Registry) {
+				reg.Register(
+					httpmock.REST("GET", "user/keys"),
+					httpmock.StringResponse(`[
+						{
+							"id": 1,
+							"key": "ssh-ed25519 asdf",
+							"title": "anything"
+						}
+					]`))
+			},
+			wantStdout: "",
+			wantStderr: "✓ Public key already exists on your account\n",
+			wantErrMsg: "",
+			opts:       AddOptions{KeyFile: "-"},
+		},
+		{
+			name:       "invalid key format",
+			stdin:      "ssh-ed25519",
+			wantStdout: "",
+			wantStderr: "X Error: provided key is not in a valid format\n",
+			wantErrMsg: "SilentError",
+			opts:       AddOptions{KeyFile: "-"},
+		},
+	}
 
-	stdin.WriteString("PUBKEY")
+	for _, tt := range tests {
+		ios, stdin, stdout, stderr := iostreams.Test()
+		ios.SetStdinTTY(false)
+		ios.SetStdoutTTY(true)
+		ios.SetStderrTTY(true)
 
-	tr := httpmock.Registry{}
-	defer tr.Verify(t)
+		stdin.WriteString(tt.stdin)
 
-	tr.Register(
-		httpmock.REST("POST", "user/keys"),
-		httpmock.StringResponse(`{}`))
+		reg := &httpmock.Registry{}
 
-	err := runAdd(&AddOptions{
-		IO: ios,
-		Config: func() (config.Config, error) {
+		tt.opts.IO = ios
+		tt.opts.HTTPClient = func() (*http.Client, error) {
+			return &http.Client{Transport: reg}, nil
+		}
+		if tt.httpStubs != nil {
+			tt.httpStubs(reg)
+		}
+		tt.opts.Config = func() (config.Config, error) {
 			return config.NewBlankConfig(), nil
-		},
-		HTTPClient: func() (*http.Client, error) {
-			return &http.Client{Transport: &tr}, nil
-		},
-		KeyFile: "-",
-		Title:   "my sacred key",
-	})
-	assert.NoError(t, err)
+		}
 
-	assert.Equal(t, "", stdout.String())
-	assert.Equal(t, "✓ Public key added to your account\n", stderr.String())
+		t.Run(tt.name, func(t *testing.T) {
+			defer reg.Verify(t)
+			err := runAdd(&tt.opts)
+			if tt.wantErrMsg != "" {
+				assert.Equal(t, tt.wantErrMsg, err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tt.wantStdout, stdout.String())
+			assert.Equal(t, tt.wantStderr, stderr.String())
+		})
+	}
 }
diff --git a/pkg/cmd/ssh-key/add/http.go b/pkg/cmd/ssh-key/add/http.go
index 1b8b7b245..9a603393d 100644
--- a/pkg/cmd/ssh-key/add/http.go
+++ b/pkg/cmd/ssh-key/add/http.go
@@ -3,21 +3,50 @@ package add
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"io"
 	"net/http"
+	"strings"
 
 	"github.com/cli/cli/v2/api"
 	"github.com/cli/cli/v2/internal/ghinstance"
+	"github.com/cli/cli/v2/pkg/cmd/ssh-key/shared"
+	"github.com/cli/cli/v2/pkg/cmdutil"
+	"github.com/cli/cli/v2/pkg/iostreams"
 )
 
-func SSHKeyUpload(httpClient *http.Client, hostname string, keyFile io.Reader, title string) error {
+func SSHKeyUpload(httpClient *http.Client, hostname string, keyFile io.Reader, title string, printSuccessMsgs bool, ios *iostreams.IOStreams) error {
 	url := ghinstance.RESTPrefix(hostname) + "user/keys"
+	cs := ios.ColorScheme()
 
 	keyBytes, err := io.ReadAll(keyFile)
 	if err != nil {
 		return err
 	}
 
+	userKey := string(keyBytes)
+	splitKey := strings.Fields(userKey)
+	if len(splitKey) < 2 {
+		fmt.Fprintf(ios.ErrOut, "%s Error: provided key is not in a valid format\n", cs.FailureIcon())
+		return cmdutil.SilentError
+	}
+
+	userKey = splitKey[0] + " " + splitKey[1]
+
+	keys, err := shared.UserKeys(httpClient, hostname, "")
+	if err != nil {
+		return err
+	}
+
+	for _, k := range keys {
+		if k.Key == userKey {
+			if printSuccessMsgs && ios.IsStdoutTTY() {
+				fmt.Fprintf(ios.ErrOut, "%s Public key already exists on your account\n", cs.SuccessIcon())
+			}
+			return nil
+		}
+	}
+
 	payload := map[string]string{
 		"title": title,
 		"key":   string(keyBytes),
@@ -48,5 +77,8 @@ func SSHKeyUpload(httpClient *http.Client, hostname string, keyFile io.Reader, t
 		return err
 	}
 
+	if printSuccessMsgs {
+		fmt.Fprintf(ios.ErrOut, "%s Public key added to your account\n", cs.SuccessIcon())
+	}
 	return nil
 }
diff --git a/pkg/cmd/ssh-key/list/list.go b/pkg/cmd/ssh-key/list/list.go
index d057b198c..0c0cbcd0b 100644
--- a/pkg/cmd/ssh-key/list/list.go
+++ b/pkg/cmd/ssh-key/list/list.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/cli/cli/v2/internal/config"
 	"github.com/cli/cli/v2/internal/text"
+	"github.com/cli/cli/v2/pkg/cmd/ssh-key/shared"
 	"github.com/cli/cli/v2/pkg/cmdutil"
 	"github.com/cli/cli/v2/pkg/iostreams"
 	"github.com/cli/cli/v2/utils"
@@ -55,7 +56,7 @@ func listRun(opts *ListOptions) error {
 
 	host, _ := cfg.Authentication().DefaultHost()
 
-	sshKeys, err := userKeys(apiClient, host, "")
+	sshKeys, err := shared.UserKeys(apiClient, host, "")
 	if err != nil {
 		return err
 	}
diff --git a/pkg/cmd/ssh-key/list/http.go b/pkg/cmd/ssh-key/shared/user_keys.go
similarity index 91%
rename from pkg/cmd/ssh-key/list/http.go
rename to pkg/cmd/ssh-key/shared/user_keys.go
index 7275615e0..57f309d19 100644
--- a/pkg/cmd/ssh-key/list/http.go
+++ b/pkg/cmd/ssh-key/shared/user_keys.go
@@ -1,4 +1,4 @@
-package list
+package shared
 
 import (
 	"encoding/json"
@@ -18,7 +18,7 @@ type sshKey struct {
 	CreatedAt time.Time `json:"created_at"`
 }
 
-func userKeys(httpClient *http.Client, host, userHandle string) ([]sshKey, error) {
+func UserKeys(httpClient *http.Client, host, userHandle string) ([]sshKey, error) {
 	resource := "user/keys"
 	if userHandle != "" {
 		resource = fmt.Sprintf("users/%s/keys", userHandle)