Magnolia warblers are small birds and only weigh 0.2-0.5 ounces (6-15 grams), with a length that ranges from 4.3-5.1 inches (11-13 centimeters) and a wingspan of 6.3-9.9 inches (16-20 centimeters).  

Magnolia Warblers fly across the Gulf of Mexico and the Eastern half of the North America in the spring and fall to reach their breeding and wintering grounds, respectively. In the winter, they are most common in the Yucatan Peninsula of Mexico but are found throughout Mexico, Central America and the West Indies. During the breeding season, they can be found mainly throughout Canada and the Northeastern and Great Lakes regions of the United States.

During their seasonal migration, magnolia warblers prefer to spend time in low trees and shrubs along forest edges, wood lots and parks. In winter, they can be found anywhere from sea level to 5,000 feet in various habitats, including cacao plantations, shade coffee farms (as opposed to sun coffee farms that do not provide adequate habitat), orchards, mixed forests and thickets. In the breeding season they prefer dense stands of young evergreen trees or stands of mixed evergreen/broad-leaved trees.

Their average life span is unknown. The oldest recorded magnolia warbler lived for at least 8 years and 11 months.  

The males have two songs during the breeding season. One song is used to defend their territory against other males and consists of three short phrases with a slightly accented ending. The other song is used to attract and communicate with a mate. This song also consists of three short phrases but is less sweet and has a more accented ending. Both males and females have call notes that they use if potential predators are nearby and to communicate in the wintering grounds, where no singing takes place.

During the breeding season, they eat various insects, including moth caterpillars, leafhoppers, beetles, aphids and spiders. However, when insects are scarce, they will occasionally eat berries. Their diet during migration and winter is largely unknown, although it is likely very similar to that of the breeding season.

Magnolia warblers are active during the daytime. During migration, many of them travel at nighttime.

Breeding territories are defended by males, while both sexes each defend separate territories in the wintering grounds. During migration and in the winter, they can be seen foraging among flocks of many different species.  

Male magnolia warblers arrive at the breeding grounds about 10 days before females in order to establish their territories. Males will spread their tail feathers and show off the white spots on their tails; they also do this to scare off predators and attract females.

Once a pair mates, they choose a well-hidden nest site among dense evergreen trees, such as spruce, balsam fir and hemlock. With some help from males, females create a nest made of grasses, weeds stalks and twigs lined with horsehair fungus. Magnolia warblers have clutches of three to five white eggs with variable speckles of brown, lavender, olive and gray. The females incubate the eggs for 11 to 13 days, and the offspring fledge about eight to 10 days after hatching. Both parents feed the young for up to 25 more days before they are left to fend for themselves. Females typically brood one time per year.

Although magnolia warblers' population has seen an increase in the last 20 years, they are still vulnerable to habitat loss due to climate change and deforestation, as well as mortality due to collisions with human structures during migration Their current wintering grounds are also at risk due to the increasing prevalence of sun coffee farms, which now make up three-quarters of the world's coffee farms. Sun coffee farms destroy native forest habitats and often use harmful pesticides and fertilizers that poison the environment.