First Minister Carwyn Jones and Welsh Language Commissioner Meri Huws will also join the "Making Welsh Work" conference at Bangor University.
Mr Jones called the event "timely" and said having more chances to use the language were key to learning it.
Gwynedd council and Natural Resources Wales are among those taking part.
The best ways to encourage people to speak Welsh at work will be discussed on Friday by more than 100 delegates from organisations across Wales.