It is powered by the same processor as the flagship iPhone 11 Pro, but lacks multiple rear cameras.
The handset costs the same as the original SE in the US, but is more expensive in other markets.
The iPhone SE is priced at $399 in the US and £419 in the UK.
One analyst said that having a mid-range phone again could help Apple compete for new customers against rivals such as Samsung and Google, which have a strong presence in that market sector.
"Once you buy an iPhone you are more likely to buy another one," said Dan Iver from Wedbush Securities.
Despite Covid-19 causing lower demand, smartphone makers continue to release models. Earlier this week, OnePlus unveiled new models, and last month Huawei launched its flagship P40 range.
In February, Apple warned that the coronavirus lockdown in China would impact iPhone production and lower sales.
Physical stores, including Apple's, remain closed in many countries.
