Van Persie is set to face his former employers Arsenal for the first time this weekend since moving to Old Trafford in a reported £24million move in the summer.
The Dutchman has continued the form that saw him strike 37 times for the Gunners last season by scoring nine goals in 12 appearances for United.
Giggs said: "When a ready-made, world-class player comes into the team it gives everybody a lift.
"We're like the supporters - we look forward to playing with and seeing quality players come into the team.
"Robin is certainly that. He's proven that with his goals and all-round play since he's come to the club."
Giggs, who is now in his 22nd season with United, also points out that Van Persie has brought more to United than goals.
The 38-year-old added: "Robin's set-piece delivery has been really important to us.
"It's a big plus this season that we're scoring from set-pieces and corners.
"That's something we haven't done over the last few years as often as we'd have liked.
"So with Robin it's not just goals you get. He's helped add more goals to the scoresheet and helped a few different names get on there."
Giggs remains a key player at United although his role is now more limited.
His start in Wednesday's Capital One Cup defeat at Chelsea, in which he scored twice, was his first in over a month.
He has enjoyed some fine encounters with Arsenal over the years, not least when United thrashed the Gunners 8-2 on their last visit to Old Trafford in August last year.
The Welshman is certainly not expecting a repeat of that scoreline in this season's corresponding fixture on Saturday.
He said: "No, I think that was one of those fluke performances.
"We always expect a tough performance against Arsenal, both home and away. It's no different this time.
"They got off to a really good start. They've stuttered a little in recent weeks but they have plenty of quality."