Ron Harper Jr., the Celtics’ top two-way player, is signing a two-year standard contract with Boston, his agent told ESPN’s Shams Charania on Saturday.

The contract conversion will allow Harper, who’s seen action in 19 of the Celtics’ last 27 games, to play in the postseason. The Celtics made similar moves with Neemias Queta late in the 2023-24 season and JD Davison last April.

Primarily a Celtics G Leaguer for the first half of this season, Harper has been a regular contributor for the big club since early February. His best outings came on Feb. 4 against Houston, when he tallied 11 points and nine rebounds while playing stingy defense on Kevin Durant in his first NBA start, and on March 10 against San Antonio, when he scored a career-high 22 points and went 6-for-9 from 3-point range.

Harper, who won his two-way spot through a training camp tryout, also participated in the Rising Stars showcase during NBA All-Star weekend, and in the Shooting Stars event alongside his father, Ron, a five-time NBA champion, and his younger brother, Dylan, the No. 2 pick in the 2025 NBA Draft.

“We all think Ron is one of the best players in the G League all season,” Celtics president of basketball operations Brad Stevens said in February. “Whenever his opportunity was going to come, he was going to take advantage of it. … He’s a stud. He’s a really good player, and he’s been great for us for the better part of two years, somewhere within our system.”

The 25-year-old wing has seen substantially more NBA playing time than Celtics draftees Amari Williams and Max Shulga, who had their two-way deals converted in April and May, respectively.

Boston’s delay in signing him to a standard deal was financially driven. Because the Celtics have operated just below the NBA’s luxury tax line since the trade deadline, they have needed to carefully time their roster moves to avoid exceeding it. Williams’ and Shulga’s cheaper rookie contracts gave the team more financial flexibility while it pieced together the back end of its roster.

Signing Harper, who is unlikely to see consistent postseason minutes if the Celtics are fully healthy, brings Boston back to the NBA-mandated minimum of 14 rostered players. He fills the spot previously occupied by veteran big man Charles Bassey, whose second 10-day contract expired on Saturday.

The Celtics have one open spot on their 15-man roster. They will host the Toronto Raptors on Sunday at TD Garden (3:30 p.m.).