It’s often said he did. And yes, I know there’s no doubt the Chinese invented pasta first. But there’s no reason Europeans might not have invented them independently prior to any contact with the Far East – they had wheat, after all. What’s the Straight Dope?
There are some reasonable sounding cites that say that the Italians did invent it independently or at least they got it from somewhere before Marco Polo.
Here is one:
“Popular legend has it that Marco Polo introduced pasta to Italy following his exploration of the Far East in the late 13th century; however, we can trace pasta back as far as the fourth century B.C., where an Etruscan tomb showed a group of natives making what appears to be pasta. The Chinese were making a noodle-like food as early as 3000 B.C. And Greek mythology suggests that the Greek God Vulcan invented a device that made strings of dough (the first spaghetti!).”
By anyone in any position to know? I doubt it. As Shagnasty says it’s well attested to in Europe well before Marco Polo’s time.
There’s far more doubt that he even made it to China.
Maybe so, but I’ve never heard of pasta being mentioned in surviving Roman cookbooks.
Here’s what Cecil has to say on the subject, admittedly a throw away at the end of a column on another matter:
http://www.straightdope.com/classics/a2_036.html
FWIW, I seem to recall that Marco Polo actually refers to the Chinese eating vermicelli, which would seem to put the kibosh on the idea that he was unacquainted with pasta before making his trip (if he actually made it to China, about which I am dubious).
wikipedia article aside, I just finished a course “From Yao to Mao: 5000 years of Chinese history” from the teaching company and in it, the professor states that not only did Marco Polo reach China but he spent time working as an administrator for the dynasty. (I have to go over my notes to find the exact details if you really want them).
No comment on the pasta thing though. 
Here’s what seems to be a fairly balanced and accurate history of pasta:
But the surviving Roman cookbooks are pretty clearly recipes of gourmet dining for the rich nobles. Pasta would be unlikely to be mentioned in such cookbooks.
Heck, even modern cookbooks don’t have many recipes for cooking pasta. (What’s there to say? Boil a pot of water, add pasta, remove when done. Even guys can cook spaghetti!) Modern cookbooks dealing with pasta (‘Italian cookbooks’) spend most of their time on the sauces and accompanying dishes, not on cooking the pasta.
Did the professor explain why Marco Polo never mentioned tea?
I wish! I’ve tried, believe me I’ve tried. How long do you have to cook it before it turns red?
I’d be more curious as to why he never mentioned the Great Wall.
Anyway, the Polo-was-a-liar theory is discussed here.