How can I serialize and deserialize a type with a string member that contains “raw” JSON, without escaping the JSON in the process

Your question is, How can I serialize and deserialize a type with a string member that contains “raw” JSON, without escaping the JSON in the process?

This can be done via a custom JsonConverter that reads and writes raw JSON using JsonWriter.WriteRawValue() and JRaw.Create():

public class RawConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        throw new NotImplementedException();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return null;
        var raw = JRaw.Create(reader);
        return raw.ToString();
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var s = (string)value;
        writer.WriteRawValue(s);
    }
}

Then apply it to your type as follows:

public class Employee
{
    public int EmpId { get; set; }
    public string EmpName { get; set; }
    // **Note** : I'm not using List<Address> data type for Address, instead of I want list of address in JSON string
    [JsonConverter(typeof(RawConverter))]
    public string Address { get; set; }
}

public class RootObject
{
    public List<Employee> Employees { get; set; }
}

Sample fiddle.

Note that the raw JSON string must represent valid JSON. If it does not, then the JSON created will be unreadable. If you want to guarantee that the JSON literal is valid, you can keep the JSON in a parsed state internally:

public class Employee
{
    public int EmpId { get; set; }
    public string EmpName { get; set; }

    [JsonProperty("Address")]
    JToken AddressToken { get; set; }

    [JsonIgnore]
    public string Address
    {
        get
        {
            if (AddressToken == null)
                return null;
            return AddressToken.ToString(Formatting.Indented); // Or Formatting.None if you prefer
        }
        set
        {
            if (value == null)
                AddressToken = null;
            else
                // Throw an exception if value is not valid JSON.
                AddressToken = JToken.Parse(value);
        }
    }
}

A converter is not needed for this implementation.