A wetness notification system for detecting and notifying wetness in a clothing article that is configured for absorbing urine, the wetness notification system being characterized by: a detecting unit that includes a sleeve body, a mounting seat combined with said sleeve body, a moisture detector mounted on said mounting seat, and configured to output a notification signal when a surrounding moisture level detected thereby is greater than a threshold moisture level, a casing, a wireless transmitter disposed in said casing, a processor disposed in said casing, electrically connected to said moisture detector and said wireless transmitter, and configured to receive the notification signal outputted by said moisture detector and to transmit the notification signal through said wireless transmitter, and a battery disposed in said casing and configured to provide electricity to said moisture detector, said processor and said wireless transmitter; a clip unit that includes a first portion removably inserted into said sleeve body, a curved second portion extending from said first portion, and a third portion extending from said curved second portion, removably supporting said casing, and configured to cooperate with said first portion to clip said detecting unit onto the clothing article in a manner that said sleeve body and said mounting seat are disposed at an inner side of the clothing article and that said third portion is disposed at an outer side of the clothing article; a receiver unit that includes a wireless receiver configured to communicate wirelessly with said wireless transmitter for receiving the notification signal therefrom, a notifying module, and a controller electrically connected to said wireless receiver and said notifying module and configured to drive said notifying module to output a wetness notification in response to receipt of the notification signal from said wireless receiver; and a sampling unit that includes a substrate made of flexible material and removably attached to said mounting seat, and at least one sampling element disposed on said substrate for contacting and sampling urine within the clothing article for urinalysis. a detecting unit that includes a sleeve body, a mounting seat combined with said sleeve body, a moisture detector mounted on said mounting seat, and configured to output a notification signal when a surrounding moisture level detected thereby is greater than a threshold moisture level, a casing, a wireless transmitter disposed in said casing, a processor disposed in said casing, electrically connected to said moisture detector and said wireless transmitter, and configured to receive the notification signal outputted by said moisture detector and to transmit the notification signal through said wireless transmitter, and a battery disposed in said casing and configured to provide electricity to said moisture detector, said processor and said wireless transmitter; a sleeve body, a mounting seat combined with said sleeve body, a moisture detector mounted on said mounting seat, and configured to output a notification signal when a surrounding moisture level detected thereby is greater than a threshold moisture level, a casing, a wireless transmitter disposed in said casing, a processor disposed in said casing, electrically connected to said moisture detector and said wireless transmitter, and configured to receive the notification signal outputted by said moisture detector and to transmit the notification signal through said wireless transmitter, and a battery disposed in said casing and configured to provide electricity to said moisture detector, said processor and said wireless transmitter; a clip unit that includes a first portion removably inserted into said sleeve body, a curved second portion extending from said first portion, and a third portion extending from said curved second portion, removably supporting said casing, and configured to cooperate with said first portion to clip said detecting unit onto the clothing article in a manner that said sleeve body and said mounting seat are disposed at an inner side of the clothing article and that said third portion is disposed at an outer side of the clothing article; a first portion removably inserted into said sleeve body, a curved second portion extending from said first portion, and a third portion extending from said curved second portion, removably supporting said casing, and configured to cooperate with said first portion to clip said detecting unit onto the clothing article in a manner that said sleeve body and said mounting seat are disposed at an inner side of the clothing article and that said third portion is disposed at an outer side of the clothing article; a receiver unit that includes a wireless receiver configured to communicate wirelessly with said wireless transmitter for receiving the notification signal therefrom, a notifying module, and a controller electrically connected to said wireless receiver and said notifying module and configured to drive said notifying module to output a wetness notification in response to receipt of the notification signal from said wireless receiver; and a sampling unit that includes a substrate made of flexible material and removably attached to said mounting seat, and at least one sampling element disposed on said substrate for contacting and sampling urine within the clothing article for urinalysis.