Linkten dönen veriyi https://javiercbk.github.io/json_to_dart/ sitesini kullanarak dart için classlarını aldım sonra fonksiyonunu one göre düzenledim.

ArticleModelClass

class ArticleModel {
  String? status;
  int? totalResults;
  List<Articles>? articles;

  ArticleModel({this.status, this.totalResults, this.articles});

  ArticleModel.fromJson(Map<String, dynamic> json) {
    status = json['status'];
    totalResults = json['totalResults'];
    if (json['articles'] != null) {
      articles = <Articles>[];
      json['articles'].forEach((v) {
        articles!.add(Articles.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['status'] = status;
    data['totalResults'] = totalResults;
    if (articles != null) {
      data['articles'] = articles!.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Articles {
  Source? source;
  String? author;
  String? title;
  String? description;
  String? url;
  String? urlToImage;
  String? publishedAt;
  String? content;

  Articles(
      {this.source,
      this.author,
      this.title,
      this.description,
      this.url,
      this.urlToImage,
      this.publishedAt,
      this.content});

  Articles.fromJson(Map<String, dynamic> json) {
    source = json['source'] != null ? Source.fromJson(json['source']) : null;
    author = json['author'];
    title = json['title'];
    description = json['description'];
    url = json['url'];
    urlToImage = json['urlToImage'];
    publishedAt = json['publishedAt'];
    content = json['content'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    if (source != null) {
      data['source'] = source!.toJson();
    }
    data['author'] = author;
    data['title'] = title;
    data['description'] = description;
    data['url'] = url;
    data['urlToImage'] = urlToImage;
    data['publishedAt'] = publishedAt;
    data['content'] = content;
    return data;
  }
}

class Source {
  String? id;
  String? name;

  Source({this.id, this.name});

  Source.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = <String, dynamic>{};
    data['id'] = id;
    data['name'] = name;
    return data;
  }
}

futureGetMethod

Future<List<Articles>?> getNews() async {
    final response = await http.get(Uri.parse(
        "https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=7457ce54364a42eb9e0ecfdaf43c375c"));

    if (response.statusCode == 200) {
      var jsonData = jsonDecode(response.body);
      ArticleModel model = ArticleModel.fromJson(jsonData);
      if (model.status == "ok") {
        return model.articles;
      }
    }
  }