C# version of Array.Unshift() from UnityScript?

As per my understanding .Unshift method adds items to the start of array and return new length of array.

You can use List<T> collection in C#. To add items at first position of (prepond) to list use following way.

List<T>.Insert(0, item); // this will insert item at first position

Also you can convert this list to array using .ToArray() method of list.