Atif Khan, from Park Lane, in Tipton, was arrested in London on Monday, October 11, in connection with the death of Kimani Martin in the early hours of June 20, just weeks after turning 18.
Kimani was shot with a shotgun at 1.30am while he was in a taxi in Dudley Road East, Tividale, on June 20.
Three special constables from West Midlands Police, who were nearby, came across the scene and tended to the teenager but nothing could be done to save him. He was taken to hospital and pronounced dead a short time later.
The 25-year-old has now been charged with Kimani’s murder and appeared at Birmingham Magistrates Court this morning.
Three men have already been charged with Mr Martin's murder. Kisharne Campbell, 23, and Usman Amjad, 21 – both of no fixed address – as well as 19-year-old Luke Adams, from Walsall, are now on remand in prison.
All three deny murder and are due to stand trial in May next year.
A 25-year-old man remains on police bail and enquiries continue.
After his death, a family tribute described Kimani as “jovial, loving and caring”.
"He had a big heart, he loved everyone and was willing to help anyone. He loved his family dearly and he lived life to the fullest," they said.
"We are deeply saddened and distraught over the loss of Kimani so suddenly."
Police are continuing to appeal for anyone with information to contact them on 101, quoting crime reference number 20/1126386/21.