Being notorious takes more than being well-known. You have to be well-known in an unfavorable light.
The Online Etymology Dictionary says the word dates to 1548 and has had a negative connotation since the 17th century "from frequent association with derogatory nouns."
WRONG: "He always watched out for his family and others. He was notorious for helping."
RIGHT: "He was notorious for killing entire families because of the transgressions of a single member."
Less often confused is infamous, which requires a bad reputation.
Infamous has its negative connotation from its infancy in the 14th century.
WRONG: "I always have a good time at Jeff's charity functions. Last year's ball was infamous."
RIGHT: "The cops will no doubt show up soon. Jeff's charity functions are infamous for devolving into drunken brawls."