Yes and no.

Some infrared leds are invisible and some leds emit a slight red glow. If the leds are invisible to the naked eye, it will be stated in the product's description as invisible leds.

No. Almost but not 100% invisible. Most pedestrians and passerbys will never know you have infrared led surveillance cameras.

We offer a 940nm led in our 56 and 104 led cameras. These 940nm leds are virtually invisible. They are only offered in two cameras.

The 850nm leds are much more common and actually put out more light per led than the 940nm. This is what is in the vast majority of our infrared cameras.

The 850nm leds put out a slight reddish or pinkish glow if you stare right straight into the camera in the dark. You won't see the leds at a glance, you have to look for the glow.
 

940nm infrared LEDs are virtually invisible to the naked eye. These LEDs produce no light that the naked human eye can see. The light from these LEDs can, however, be picked up by infrared cameras. These cameras may vary between 930 and 950nm.

The 850nm infrared LEDs have a very slight reddish glow to the LEDs themselves. The fact that they do have a very small amount of light that the human eye can see means they will illuminate better. A 850nm LED will illuminate two to three more than a 940nm LED. Operating voltage, amperage and manufacture also play vital roles in the brightness of and LED. This is how our 48LED and 28LED (850nm) cameras can illuminate as well or better than our 104LED (940nm) camera.

If a camera has 940nm infrared LEDs it will be labelled as such in the description.