When changing the domain for a site there is always a risk. There is a chance you will see a dip in rankings initially. All you can do is to try to minimise any damage:
- Setup the site on the new domain, whilst keeping the site active on the old domain (temporarily).
- Verify both domains (properties) in Google Search Console (GSC / formerly Google Webmaster Tools). Ensure that the canonical (www or non-www) versions are verified.
- Submit an XML sitemap for the new domain in GSC.
- Setup 301 (permanent) redirects from the old to new domains. (At this point, you can shut down the old site, whilst keeping the redirect in place.)
- Where possible, change any prominent backlinks to the new domain.
- Use the Change of Address tool in GSC to submit a change of address request.
Google Search Console Help - Use the change of address tool
However, there are still other SEO/business considerations, particularly if this is your company website. Customer awareness/trust etc.