England's rusty performance drew negative reviews.
"It was really poor from England...sloppy in possession, taking too long to play the pass and then getting caught," former England keeper Karen Bardsley told BBC Radio. "I didn't expect it to be that close."
There were some encouraging signs however for the European champions. Their 11 shots on target were the most in a World Cup game since 2011, and Alessia Russo's five shots on net were the most by an England player since then.
The Lionesses have also scored in each of their last 14 games in the global tournament, although Saturday's lone goal was a penalty kick from Georgia Stanway.
The nerve-jangling win was also reminiscent of their narrow 1-0 victory over Austria to open the Euro tournament a year earlier that they went on to win.
Keeper Mary Earps, who made a spectacular game-changing save in the dying minutes when she stretched to get a toe on a shot from Roseline Eloissaint, said England have plenty of work to do in their five days of training before facing Denmark on July 28.
"(The win) puts us in a good place," said the Manchester United keeper. "But for sure there's plenty we need to review and reflect on because we have set ourselves a higher standard than that."
Denmark eked out a 1-0 victory over China in the opener of their first World Cup appearance in 16 years on a late goal by Amalie Vangsgaard, joining the Lionesses atop Group D with three points apiece.
"Denmark is a different style of play (than Haiti)," said coach Sarina Wiegman.
Playing far better than a 53rd ranking, Haiti pushed England to the brink with their speed and unpredictability, and the game was a virtual coming-out party for 19-year-old Lyon midfielder Melchie Dumornay.
"First time in a World Cup and having a performance like that, I think the other two countries (Denmark and China) are going to really struggle with them," Wiegman said.
"But of course, that's not our problem. I'm just really happy that we got the win. And we have the first three points in a very hard game."
Haiti, who were forced to move their training base to the Dominican Republic because of security concerns in the Caribbean country of just under 1.5 million, celebrated Saturday's debut as a victory. Considering the gang violence and political collapse plaguing that country, just qualifying for the World Cup - they were one of the last three teams to clinch a spot - was victory in itself.
"We're very proud of our performance," coach Nicolas Delepine said. "We've worked very hard and for us it was a huge test. We were up against the European champions.
"We weren't sure how we were going to play, but we were able to pull it out of the bag. We were very close to England, but there are always things we can do better."
Haiti next face China on July 28th.
