The bitcoin symbol was added to unicode in June 2017 with the release of version 10.0. The code point assigned to the bitcoin symbol is U+20BF (₿). It was categorized as a currency symbol.

some digging on unicode.org mail-arch:

• 2011/12/Jun | António Martins | Bitcoin sign

  • Here: https://en.bitcoin.it/wiki/Promotional_graphics Maybe this will be suitable for encoding in the future. Looks like a variant of U+0E3F THAI CURRENCY SYMBOL BAHT, with double stroke showing only above and bellow the "B". -- ____. António MARTINS-Tuválkin | ()| <antonio_at_tuvalkin.web.pt> Não me invejo de quem tem |####| PT-1500-111 LISBOA carros, parelhas e montes | +351 934 821 700, +351 217 150 939 só me invejo de quem bebe | ICQ:193279138 http://tuvalkin.web.pt/%c2%a0%c2%a0 a água em todas as fontes |

• 2011/13/Jun | Roozbeh Pournader | Re: Bitcoin sign

  • This was discussed in the latest UTC meeting based on a proposal. The committee asked for evidence of plain text use (which was not given) and some research into its trademark status, IIRC.

• 2011/09/Jul | Luke-Jr | Re: Bitcoin sign

  • Just realized this is actually already supported by Unicode: B⃦ There is also B⃫ with diagonal slashes instead...

• 2015/03/Sep | Ken Shirriff | Upcoming proposal for Bitcoin sign

  • I'm putting together a proposal for the Bitcoin sign to be added to Unicode, so I wanted to check here if people have any comments/concerns/objections. [...]

• 2015/07/Sep | Martin J. Dürst | Re: Upcoming proposal for Bitcoin sign

  • You write "The bitcoin sign and baht symbol are two unrelated symbols that have some visual similarity.", but don't really give any supporting information for that claim. [...]

• 2015/07/Sep | Ken Shirriff | Re: Upcoming proposal for Bitcoin sign

  • Thanks for your comments, Martin. Asmus Freytag gave a detailed response, but I'd like to add a few things. [...]

• 2015/07/Sep | Michael Everson | Re: Upcoming proposal for Bitcoin sign

  • Just want to say, I don’t think this one is a runner right now. I spent many months recently working with people associated with Bitcoin and they could not decide what they wanted to do.