The standard advice for writing a bio is to write in the third person (as though someone else is writing about you). However, there are a few exceptions to the “third person rule”.
Here are four situations when you should write your bio in first person instead of third-person:
1) when you are writing a mini-bio for Twitter, Facebook, Instagram and other social networking sites. Social networks are informal gathering places, so a less formal bio is appropriate (see examples here).
2) when you are applying for a program or scholarship. Applications work best when they are written in a personal voice, e.g. “I would like to attend X school because…” rather than “John would like to attend X school because…”
3) when the person or agency requesting your bio has specified that they want it in first person
4) if you simply feel more comfortable writing your bio in first person (it’s your choice!)
Don’t get too hung up on the “third person” or “first person” issue. There’s no absolute right or wrong, just conventions. Third person tends to sound formal and professional, whereas first person sounds more informal and friendly.
If you do decide to write your bio in first person, you will also need a version of it in third person for occasions such as speaking engagements when someone else is introducing you.