Welsh star Xu was making her first appearance at Wimbledon and showed glimpses of quality in a match that ebbed and flowed.
But Raducanu proved too strong and booked her place in the second round to cheers of delight from the crowd.
“I’m super pleased to have come through that match – it’s so difficult playing another Brit first round,” she said in her on-court interview.
“When the draw came out, I can’t say that I was loving it. Mimi is a very dangerous player – she’s so young and got some amazing weapons at her disposal.
“I just want to thank everyone for the support on both sides – it was a really nice atmosphere.”
Raducanu, once a precocious teenager but now the senior player, asserted her authority from the off, breaking Xu’s serve in the opening game.
The latter showed promise throughout, hitting eight winners to Raducanu’s seven in the first set, but unforced errors were her undoing.
Raducanu made relatively light work of the opening set, and it seemed she might breeze to victory after breaking early in the second, too.
But Xu, despite her uncertainty on serve, broke back and later broke again, demonstrating her ability to compete with Britain’s best.
But Raducanu got the crucial break at 4-2, eventually serving out the match and progressing into the second round, where she will face Marketa Vondrousova from the Czech Republic.
“Sometimes it’s difficult in the moment with nerves and adrenaline, you don’t really have an idea of what’s going on,” Raducanu said.
“I think I had some really good patches and then some moments where I lost my focus and Mimi was able to come back.
“I’m really happy with how I toughed it out in the really crucial games and won the important points today.”
On the support from a lively crowd, she added: “I’m glad people are having fun today – I saw a Champagne cork fly onto the court.
“It’s really nice to be back and I just use the support, and I love playing in this atmosphere. It’s my favourite tournament by far. I’m just so happy to get another match here.”
