diff --git a/src/main/java/seedu/address/logic/commands/RemarkCommand.java b/src/main/java/seedu/address/logic/commands/RemarkCommand.java
index 3190aaded32..9678ef9037d 100644
--- a/src/main/java/seedu/address/logic/commands/RemarkCommand.java
+++ b/src/main/java/seedu/address/logic/commands/RemarkCommand.java
@@ -2,10 +2,15 @@
 
 import static seedu.address.commons.util.CollectionUtil.requireAllNonNull;
 import static seedu.address.logic.parser.CliSyntax.PREFIX_REMARK;
+import static seedu.address.model.Model.PREDICATE_SHOW_ALL_PERSONS;
 
+import java.util.List;
+
+import seedu.address.commons.core.Messages;
 import seedu.address.commons.core.index.Index;
 import seedu.address.logic.commands.exceptions.CommandException;
 import seedu.address.model.Model;
+import seedu.address.model.person.Person;
 import seedu.address.model.person.Remark;
 
 /**
@@ -23,7 +28,8 @@ public class RemarkCommand extends Command {
             + "Example: " + COMMAND_WORD + " 1 "
             + PREFIX_REMARK + "Likes to swim.";
 
-    public static final String MESSAGE_ARGUMENTS = "Index: %1$d, Remark: %2$s";
+    public static final String MESSAGE_ADD_REMARK_SUCCESS = "Added remark to Person: %1$s";
+    public static final String MESSAGE_DELETE_REMARK_SUCCESS = "Removed remark from Person: %1$s";
 
     private final Index index;
     private final Remark remark;
@@ -40,7 +46,29 @@ public RemarkCommand(Index index, Remark remark) {
     }
     @Override
     public CommandResult execute(Model model) throws CommandException {
-        throw new CommandException(String.format(MESSAGE_ARGUMENTS, index.getOneBased(), remark));
+        List<Person> lastShownList = model.getFilteredPersonList();
+
+        if (index.getZeroBased() >= lastShownList.size()) {
+            throw new CommandException(Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
+        }
+
+        Person personToEdit = lastShownList.get(index.getZeroBased());
+        Person editedPerson = new Person(personToEdit.getName(), personToEdit.getPhone(), personToEdit.getEmail(),
+                personToEdit.getAddress(), remark, personToEdit.getTags());
+
+        model.setPerson(personToEdit, editedPerson);
+        model.updateFilteredPersonList(PREDICATE_SHOW_ALL_PERSONS);
+
+        return new CommandResult(generateSuccessMessage(editedPerson));
+    }
+
+    /**
+     * Generates a command execution success message based on whether the remark is added to or removed from
+     * {@code personToEdit}.
+     */
+    private String generateSuccessMessage(Person personToEdit) {
+        String message = !remark.value.isEmpty() ? MESSAGE_ADD_REMARK_SUCCESS : MESSAGE_DELETE_REMARK_SUCCESS;
+        return String.format(message, personToEdit);
     }
 
     @Override
diff --git a/src/test/java/seedu/address/logic/commands/RemarkCommandTest.java b/src/test/java/seedu/address/logic/commands/RemarkCommandTest.java
index d92598a0440..35d274a7b37 100644
--- a/src/test/java/seedu/address/logic/commands/RemarkCommandTest.java
+++ b/src/test/java/seedu/address/logic/commands/RemarkCommandTest.java
@@ -6,31 +6,104 @@
 import static seedu.address.logic.commands.CommandTestUtil.VALID_REMARK_AMY;
 import static seedu.address.logic.commands.CommandTestUtil.VALID_REMARK_BOB;
 import static seedu.address.logic.commands.CommandTestUtil.assertCommandFailure;
-import static seedu.address.logic.commands.RemarkCommand.MESSAGE_ARGUMENTS;
+import static seedu.address.logic.commands.CommandTestUtil.assertCommandSuccess;
+import static seedu.address.logic.commands.CommandTestUtil.showPersonAtIndex;
 import static seedu.address.testutil.TypicalIndexes.INDEX_FIRST_PERSON;
 import static seedu.address.testutil.TypicalIndexes.INDEX_SECOND_PERSON;
 import static seedu.address.testutil.TypicalPersons.getTypicalAddressBook;
 
 import org.junit.jupiter.api.Test;
 
+import seedu.address.commons.core.Messages;
+import seedu.address.commons.core.index.Index;
+import seedu.address.model.AddressBook;
 import seedu.address.model.Model;
 import seedu.address.model.ModelManager;
 import seedu.address.model.UserPrefs;
+import seedu.address.model.person.Person;
 import seedu.address.model.person.Remark;
+import seedu.address.testutil.PersonBuilder;
 
 /**
  * Contains integration tests (interaction with the Model) and unit tests for RemarkCommand.
  */
 public class RemarkCommandTest {
 
+    private static final String REMARK_STUB = "Some remark";
+
     private Model model = new ModelManager(getTypicalAddressBook(), new UserPrefs());
 
     @Test
-    public void execute() {
-        final Remark remark = new Remark("Some remark");
+    public void execute_addRemarkUnfilteredList_success() {
+        Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
+        Person editedPerson = new PersonBuilder(firstPerson).withRemark(REMARK_STUB).build();
+
+        RemarkCommand remarkCommand = new RemarkCommand(INDEX_FIRST_PERSON, new Remark(editedPerson.getRemark().value));
+
+        String expectedMessage = String.format(RemarkCommand.MESSAGE_ADD_REMARK_SUCCESS, editedPerson);
+
+        Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
+        expectedModel.setPerson(firstPerson, editedPerson);
+
+        assertCommandSuccess(remarkCommand, model, expectedMessage, expectedModel);
+    }
+
+    @Test
+    public void execute_deleteRemarkUnfilteredList_success() {
+        Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
+        Person editedPerson = new PersonBuilder(firstPerson).withRemark("").build();
+
+        RemarkCommand remarkCommand = new RemarkCommand(INDEX_FIRST_PERSON,
+                new Remark(editedPerson.getRemark().toString()));
+
+        String expectedMessage = String.format(RemarkCommand.MESSAGE_DELETE_REMARK_SUCCESS, editedPerson);
+
+        Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
+        expectedModel.setPerson(firstPerson, editedPerson);
+
+        assertCommandSuccess(remarkCommand, model, expectedMessage, expectedModel);
+    }
+
+    @Test
+    public void execute_filteredList_success() {
+        showPersonAtIndex(model, INDEX_FIRST_PERSON);
+
+        Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
+        Person editedPerson = new PersonBuilder(model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased()))
+                .withRemark(REMARK_STUB).build();
+
+        RemarkCommand remarkCommand = new RemarkCommand(INDEX_FIRST_PERSON, new Remark(editedPerson.getRemark().value));
+
+        String expectedMessage = String.format(RemarkCommand.MESSAGE_ADD_REMARK_SUCCESS, editedPerson);
+
+        Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
+        expectedModel.setPerson(firstPerson, editedPerson);
+
+        assertCommandSuccess(remarkCommand, model, expectedMessage, expectedModel);
+    }
+
+    @Test
+    public void execute_invalidPersonIndexUnfilteredList_failure() {
+        Index outOfBoundIndex = Index.fromOneBased(model.getFilteredPersonList().size() + 1);
+        RemarkCommand remarkCommand = new RemarkCommand(outOfBoundIndex, new Remark(VALID_REMARK_BOB));
+
+        assertCommandFailure(remarkCommand, model, Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
+    }
+
+    /**
+     * Edit filtered list where index is larger than size of filtered list,
+     * but smaller than size of address book
+     */
+    @Test
+    public void execute_invalidPersonIndexFilteredList_failure() {
+        showPersonAtIndex(model, INDEX_FIRST_PERSON);
+        Index outOfBoundIndex = INDEX_SECOND_PERSON;
+        // ensures that outOfBoundIndex is still in bounds of address book list
+        assertTrue(outOfBoundIndex.getZeroBased() < model.getAddressBook().getPersonList().size());
+
+        RemarkCommand remarkCommand = new RemarkCommand(outOfBoundIndex, new Remark(VALID_REMARK_BOB));
 
-        assertCommandFailure(new RemarkCommand(INDEX_FIRST_PERSON, remark), model,
-                String.format(MESSAGE_ARGUMENTS, INDEX_FIRST_PERSON.getOneBased(), remark));
+        assertCommandFailure(remarkCommand, model, Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
     }
 
     @Test