Isiah Thomas has the most career assists by a player younger than 25, with 3,501 assists.

Interpreted as:

most assists before turning 25 years old by a player

NAME	AST	GP	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	REB	STL	BLK	TOV	PF	+/-
Isiah Thomas	3,501	321	37.3	21.6	4.0	10.9				8.3	17.6	46.9	0.4			4.7	6.2	75.9	11,979	6,931	1,293				1,174
Chris Paul	3,446	345	37.3	19.3	4.7	10.0	2.4	0.1	2.6	6.8	14.5	47.3	0.9	2.5	35.3	4.7	5.6	84.8	12,881	6,668	1,624	822	31	888	887	+612
LeBron James	3,419	505	40.4	27.6	7.0	6.8	1.7	0.9	3.3	9.9	20.9	47.2	1.4	4.2	33.0	6.5	8.8	74.0	20,402	13,927	3,537	879	432	1,663	1,011	+1927
Trae Young	3,285	353	33.8	25.5	3.7	9.3	1.0	0.1	4.1	8.1	18.6	43.7	2.5	7.1	35.1	6.7	7.7	87.6	11,941	8,990	1,302	342	51	1,461	587	-39
Stephon Marbury	3,221	392	37.7	20.0	3.0	8.2	1.2	0.2	3.3	7.0	16.5	42.8	1.2	3.9	32.0	4.7	6.0	77.4	14,792	7,830	1,168	474	62	1,280	977	-324
Luka Doncic	3,110	380	34.7	28.5	8.6	8.2	1.2	0.5	4.0	9.7	20.6	47.0	2.9	8.5	34.5	6.2	8.3	74.5	13,192	10,825	3,264	443	175	1,509	855	+712
John Wall	2,990	345	36.0	17.6	4.4	8.7	1.6	0.6	3.7	6.4	14.8	43.1	0.6	2.1	30.5	4.2	5.4	78.9	12,411	6,083	1,512	568	214	1,272	828	-176
Kevin Johnson	2,823	291	34.0	18.1	3.5	9.7	1.6	0.2	3.2	6.3	12.8	49.6	0.1	0.4	17.5	5.4	6.3	85.5	9,880	5,278	1,010	461	69	928	650
Russell Westbrook	2,741	398	34.3	19.9	4.8	6.9	1.6	0.3	3.5	7.1	16.4	43.1	0.6	2.1	30.2	5.1	6.3	81.3	13,646	7,908	1,922	637	125	1,388	949	+1116
Deron Williams	2,691	310	34.9	16.2	2.9	8.7	1.0	0.2	2.9	6.0	12.9	46.7	1.1	2.9	35.8	3.2	4.0	79.8	10,820	5,028	899	301	73	898	821	+624
Rajon Rondo	2,667	359	31.7	10.7	4.4	7.4	1.9	0.1	2.5	4.4	9.0	49.0	0.1	0.6	25.2	1.7	2.8	62.3	11,364	3,845	1,581	698	50	901	843	+1804
Tony Parker	2,548	471	33.1	15.6	3.1	5.4	1.0	0.1	2.5	6.2	12.7	48.6	0.6	1.8	31.8	2.7	3.7	71.6	15,567	7,343	1,459	484	32	1,183	953	+2554
Jason Kidd	2,515	283	36.3	12.9	5.9	8.9	2.1	0.3	3.3	4.7	12.0	39.1	1.1	3.6	31.8	2.3	3.3	70.8	10,265	3,637	1,668	582	89	948	541	+306
Baron Davis	2,421	362	34.8	15.1	3.8	6.7	1.9	0.4	2.7	5.6	13.6	41.2	1.5	4.7	32.6	2.4	3.6	65.1	12,581	5,463	1,393	687	151	967	1,033	+778
Mike Bibby	2,363	349	36.1	14.7	3.2	6.8	1.4	0.2	2.6	5.8	12.8	45.1	0.9	2.4	36.3	2.2	2.8	79.1	12,597	5,126	1,115	476	55	902	667	-384
Tyrese Haliburton	2,274	260	32.9	17.2	3.7	8.7	1.5	0.6	2.3	6.3	13.1	47.8	2.5	6.2	39.3	2.2	2.6	85.6	8,547	4,483	960	385	150	591	348	-249
Brandon Jennings	2,270	371	34.5	16.7	3.3	6.1	1.4	0.2	2.5	5.9	15.2	39.0	1.9	5.4	35.0	2.9	3.7	79.9	12,796	6,187	1,232	530	79	910	748	-528
Jrue Holiday	2,268	372	32.9	13.6	3.6	6.1	1.5	0.4	2.7	5.5	12.4	43.9	1.0	2.7	37.6	1.7	2.1	79.0	12,236	5,073	1,341	544	132	997	865	+227
De'Aaron Fox	2,151	348	32.1	19.4	3.6	6.2	1.3	0.4	2.8	7.2	15.4	46.4	1.2	3.7	32.3	3.9	5.3	73.0	11,167	6,750	1,267	458	153	967	924	-800
Ben Simmons	2,127	275	33.9	15.9	8.1	7.7	1.7	0.7	3.4	6.5	11.6	56.0	0.0	0.1	14.7	2.9	4.9	59.7	9,326	4,382	2,217	464	199	925	777	+894
Raymond Felton	2,127	319	35.4	13.6	3.4	6.7	1.4	0.2	2.7	5.0	12.5	39.9	1.0	3.1	31.8	2.6	3.4	78.5	11,296	4,343	1,078	442	60	853	736	-441
Kenny Anderson	2,116	273	32.7	15.3	3.4	7.8	1.6	0.2	2.7	5.7	13.7	41.3	0.5	1.7	31.7	3.5	4.3	81.1	8,920	4,182	925	424	49	741	593
Gilbert Arenas	2,068	376	37.3	22.5	4.2	5.5	1.8	0.2	3.4	7.3	17.0	43.2	2.1	5.6	36.8	5.7	7.1	80.3	14,026	8,445	1,576	663	91	1,271	1,194	+92
Kobe Bryant	2,060	496	33.9	21.5	5.0	4.2	1.4	0.6	2.7	7.7	16.8	45.6	0.8	2.5	33.2	5.3	6.4	83.1	16,826	10,658	2,458	714	320	1,339	1,323	+2020
Kyrie Irving	2,055	371	34.2	21.6	3.4	5.5	1.3	0.3	2.7	7.9	17.2	45.7	1.9	4.9	38.2	3.9	4.5	87.2	12,670	8,002	1,268	491	122	1,012	801	+393