diff --git a/principal/accountid.go b/principal/accountid.go
index e618a85..0d0a0cd 100644
--- a/principal/accountid.go
+++ b/principal/accountid.go
@@ -4,6 +4,7 @@ import (
 	"crypto/sha256"
 	"encoding/binary"
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"hash/crc32"
 )
@@ -63,7 +64,26 @@ func (id AccountIdentifier) Encode() string {
 	return hex.EncodeToString(id.Bytes())
 }
 
+// MarshalJSON encodes the account identifier into JSON bytes as a string.
+func (id AccountIdentifier) MarshalJSON() ([]byte, error) {
+	return json.Marshal(id.String())
+}
+
 // String returns the hexadecimal representation of the account identifier.
 func (id AccountIdentifier) String() string {
 	return id.Encode()
 }
+
+// UnmarshalJSON decodes the given JSON bytes into an account identifier from a string.
+func (id *AccountIdentifier) UnmarshalJSON(bytes []byte) error {
+	var accountID string
+	if err := json.Unmarshal(bytes, &accountID); err != nil {
+		return err
+	}
+	decoded, err := DecodeAccountID(accountID)
+	if err != nil {
+		return err
+	}
+	*id = decoded
+	return nil
+}
diff --git a/principal/accountid_test.go b/principal/accountid_test.go
index 68d5fb5..c3e1792 100644
--- a/principal/accountid_test.go
+++ b/principal/accountid_test.go
@@ -1,6 +1,7 @@
 package principal_test
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/aviate-labs/agent-go/principal"
 	"testing"
@@ -24,3 +25,18 @@ func TestAccountIdentifier(t *testing.T) {
 		}
 	}
 }
+
+func TestAccountIdentifier_MarshalJSON(t *testing.T) {
+	original := principal.NewAccountID(principal.AnonymousID, principal.DefaultSubAccount)
+	raw, err := json.Marshal(original)
+	if err != nil {
+		t.Error(err)
+	}
+	var decoded principal.AccountIdentifier
+	if err := json.Unmarshal(raw, &decoded); err != nil {
+		t.Error(err)
+	}
+	if original != decoded {
+		t.Errorf("expected %v, got %v", original, decoded)
+	}
+}
diff --git a/principal/principal.go b/principal/principal.go
index 964b99b..4ebde2f 100644
--- a/principal/principal.go
+++ b/principal/principal.go
@@ -6,6 +6,7 @@ import (
 	"crypto/sha256"
 	"encoding/base32"
 	"encoding/binary"
+	"encoding/json"
 	"fmt"
 	"github.com/fxamacker/cbor/v2"
 	"hash/crc32"
@@ -130,6 +131,11 @@ func (p Principal) MarshalCBOR() ([]byte, error) {
 	return cbor.Marshal(p.Raw)
 }
 
+// MarshalJSON converts the principal to its JSON representation as a string.
+func (p Principal) MarshalJSON() ([]byte, error) {
+	return json.Marshal(p.String())
+}
+
 // String implements the Stringer interface.
 func (p Principal) String() string {
 	return p.Encode()
@@ -139,3 +145,17 @@ func (p Principal) String() string {
 func (p *Principal) UnmarshalCBOR(bytes []byte) error {
 	return cbor.Unmarshal(bytes, &p.Raw)
 }
+
+// UnmarshalJSON converts the JSON bytes into a principal from a string.
+func (p *Principal) UnmarshalJSON(bytes []byte) error {
+	var principal string
+	if err := json.Unmarshal(bytes, &principal); err != nil {
+		return err
+	}
+	decoded, err := Decode(principal)
+	if err != nil {
+		return err
+	}
+	*p = decoded
+	return nil
+}
diff --git a/principal/principal_test.go b/principal/principal_test.go
index a74566d..0719309 100644
--- a/principal/principal_test.go
+++ b/principal/principal_test.go
@@ -1,7 +1,9 @@
 package principal_test
 
 import (
+	"bytes"
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"github.com/aviate-labs/agent-go/ic"
 	"testing"
@@ -38,3 +40,18 @@ func TestPrincipal(t *testing.T) {
 		t.Fatal("expected reserved principal")
 	}
 }
+
+func TestPrincipal_MarshalJSON(t *testing.T) {
+	original := principal.MustDecode("em77e-bvlzu-aq")
+	raw, err := original.MarshalJSON()
+	if err != nil {
+		t.Error(err)
+	}
+	var decoded principal.Principal
+	if err := json.Unmarshal(raw, &decoded); err != nil {
+		t.Error(err)
+	}
+	if !bytes.Equal(original.Raw, decoded.Raw) {
+		t.Errorf("expected %v, got %v", original, decoded)
+	}
+}