Solomon-Otabor, who scored on the opening day of the season against Norwich City, has been offered a one-year contract.
Lubala, who has been a regular in the First Team squad this season, has received terms of a year, plus a 12-month option.
London-born Solomon-Otabor entered Blues' Academy as a 15-year-old, before making his debut in August 2015.
After progressing through the age groups, the winger signed his first professional contract in June 2014, before making his debut in August 2015.
During his time as a Blues player he spent three extended spells out on loan with Bolton Wanderers, Blackpool, and most recently Portsmouth.
Solomon-Otabor helped Pompey to success in the Checkatrade Trophy Final, on penalties, but last night was substituted in the second-half as they failed to overcome Sunderland in the second leg of the League One Play-Off Semi-Final.
The 23-year-old has made 38 appearances for Blues, albeit 36 of them have been off the substitutes' bench.
Lubala, 21, made three league appearances for Garry Monk's side this season, all as substitute.
The centre-forward started the 2-0 Carabao Cup defeat at Reading in August.
Lubala, who is from Leicester, joined Blues Academy in 2014 and became a professional when he was 18.
He made his senior debut in April 2018, coming off the bench in a 3-1 league defeat at Bristol City.
Blues can confirm that Kyle McFarlane, Josh Martin, Dominic Bernard, Tommy Anderson and Kieron Dawes will be released at the end of their contracts in June.
The quintet were informed in March in order to help them get them fixed up elsewhere for next season.