diff --git a/lib/ex_secrets.ex b/lib/ex_secrets.ex
index 1815944..e61230b 100644
--- a/lib/ex_secrets.ex
+++ b/lib/ex_secrets.ex
@@ -127,11 +127,24 @@ defmodule ExSecrets do
   Supported for providers:
 
   - :system_env
+  - :dot_env
   - :azure_key_vault
   - :azure_managed_identity
   - :google_secret_manager
 
   Calling this function requires the provider to be configured with credentials that allow create secrets like Secret Admionistrator in Azure Key Vault.
+
+  ## Examples
+
+      iex> File.touch(".env.dev")
+      :ok
+      iex> Application.put_env(:ex_secrets, :providers, %{dot_env: %{path: ".env.dev"}})
+      :ok
+      iex> ExSecrets.set("TEST", "test", provider: :dot_env)
+      :ok
+      iex> Application.delete_env(:ex_secrets, :providers)
+      :ok
+      iex> File.rm(".env.dev")
   """
 
   @spec set(String.t(), String.t(), Keyword.t()) :: :ok | :error
diff --git a/lib/providers/dot_env.ex b/lib/providers/dot_env.ex
index dcddcd6..102da46 100644
--- a/lib/providers/dot_env.ex
+++ b/lib/providers/dot_env.ex
@@ -16,8 +16,17 @@ defmodule ExSecrets.Providers.DotEnv do
     end
   end
 
-  def set(_name, _value) do
-    {:error, "Not implemented"}
+  def set(name, value) do
+    path = Config.provider_config_value(:dot_env, :path)
+
+    with existing when is_nil(existing) <- get(name),
+         true <- is_binary(path),
+         :ok <- File.write(path, "#{name}=#{value}\n", [:append]) do
+      Cache.save(name, value)
+      :ok
+    else
+      _ -> {:error, "Failed to write to #{path}"}
+    end
   end
 
   def init(_) do
diff --git a/lib/providers/system_env.ex b/lib/providers/system_env.ex
index 7c6c1db..f0edd99 100644
--- a/lib/providers/system_env.ex
+++ b/lib/providers/system_env.ex
@@ -18,7 +18,6 @@ defmodule ExSecrets.Providers.SystemEnv do
 
   def set(name, value) do
     System.put_env(name, value)
-    {:ok, value}
   end
 
   def process_name() do
diff --git a/mix.exs b/mix.exs
index 573e260..a49a31c 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule ExSecrets.MixProject do
   def project do
     [
       app: :ex_secrets,
-      version: "0.3.0",
+      version: "0.3.1",
       elixir: "~> 1.13",
       build_embedded: Mix.env() == :prod,
       start_permanent: Mix.env() == :prod,