Separator/Divider in SliverList flutter

I have better solution. Wrap your widget into Column then give a conditional for build Divider. The Divider Widget will appears except on the last index. Example:

CustomScrollView(
  slivers: <Widget>[
    SliverList(
      delegate: SliverChildBuilderDelegate(
        (_, int index) {
          return Column(
            children: <Widget>[
              // Put your widget here
              YourWidget(),

              // This divider will not appears on last index
              if(index != (item.length - 1))
                const Divider(),
            ],
          );
        },
        childCount: item.length,
      ),
    ),
  ],
),

Similar as ListView.separated

  import 'dart:math' as math;

  List<String> values = List();
  for (int i = 1; i <= 50; i++) {
    values.add(i.toString());
  }

  return CustomScrollView(
    semanticChildCount: values.length,
    slivers: <Widget>[
      SliverList(
        delegate: SliverChildBuilderDelegate(
          (BuildContext context, int index) {
            final int itemIndex = index ~/ 2;
            if (index.isEven) {
              return Padding(
                  child: Text(values[itemIndex]),
                  padding: EdgeInsets.all(16));
            }
            return Divider(height: 0, color: Colors.grey);
          },
          semanticIndexCallback: (Widget widget, int localIndex) {
            if (localIndex.isEven) {
              return localIndex ~/ 2;
            }
            return null;
          },
          childCount: math.max(0, values.length * 2 - 1),
        ),
      ),
    ],
  );

Although this question is very old, I will add my answer for future readers. You simply wrap your widget with a Container and then you give the container a bottom border. Here is an example:

Container(
    decoration: BoxDecoration(
        border: Border(
            bottom: BorderSide(color: Colors.grey.shade300, width: 0.5))),
    child: YourWidget(),
  ),

Simple ways,

Using SliverFillRemaining

return CustomScrollView(
    slivers: <Widget>[
      SliverFillRemaining(
        child: ListView.separated(
            itemCount:value.length,
            //shrinkWrap: true,
            physics: NeverScrollableScrollPhysics(),
            //padding: EdgeInsets.all(0),
            separatorBuilder: (BuildContext context, int index){
              return Divider();
            },
            itemBuilder: (BuildContext context, int index) {
              //widget return
            })
      ),

Using SliverList

 SliverList(
            delegate: SliverChildBuilderDelegate(
                  (BuildContext context, int index) {
                return Column(
                  children: <Widget>[
                    SizedBox(height: 5),
                    //your main widget is here
                    SizedBox(height: 5),
                    Divider(height: 1)
                  ],
                );

              },
              childCount: model.length,
            ),
          )